On the Method of Zadig This is Essay #1 from "Science and Hebrew Tradition"
Thomas Henry Huxley

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On the Method of Zadig
by Thomas Henry Huxley
This is Essay #1 from "Science and Hebrew Tradition"


"Une marque plus sure que toutes celles de Zadig."<1>--Cuvier.

It is an usual and a commendable practice to preface the
discussion of the views of a philosophic thinker by some account
of the man and of the circumstances which shaped his life and
coloured his way of looking at things; but, though Zadig is
cited in one of the most important chapters of Cuvier's greatest
work, little is known about him, and that little might perhaps
be better authenticated than it is.

It is said that he lived at Babylon in the time of King Moabdar;
but the name of Moabdar does not appear in the list of
Babylonian sovereigns brought to light by the patience and
the industry of the decipherers of cuneiform inscriptions in
these later years; nor indeed am I aware that there is any other
authority for his existence than that of the biographer of
Zadig, one Arouet de Voltaire, among whose more conspicuous
merits strict historical accuracy is perhaps hardly to
be reckoned.

Happily Zadig is in the position of a great many other
philosophers. What he was like when he was in the flesh, indeed
whether he existed at all, are matters of no great consequence.
What we care about in a light is that it shows the way, not
whether it is lamp or candle, tallow or wax. Our only real
interest in Zadig lies in the conceptions of which he is the
putative father; and his biographer has stated these with so
much clearness and vivacious illustration, that we need hardly
feel a pang, even if critical research should prove King Moabdar
and all the rest of the story to be unhistorical, and reduce
Zadig himself to the shadowy condition of a solar myth.

Voltaire tells us that, disenchanted with life by sundry
domestic misadventures, Zadig withdrew from the turmoil of
Babylon to a secluded retreat on the banks of the Euphrates,
where he beguiled his solitude by the study of nature.
The manifold wonders of the world of life had a particular
attraction for the lonely student; incessant and patient
observation of the plants and animals about him sharpened his
naturally good powers of observation and of reasoning; until, at
length, he acquired a sagacity which enabled him to perceive
endless minute differences among objects which, to the untutored
eye, appeared absolutely alike.

It might have been expected that this enlargement of the powers
of the mind and of its store of natural knowledge could tend to
nothing but the increase of a man's own welfare and the good of
his fellow-men. But Zadig was fated to experience the vanity of
such expectations.

"One day, walking near a little wood, he saw, hastening that
way, one of the Queen's chief eunuchs, followed by a troop of
officials, who appeared to be in the greatest anxiety, running
hither and thither like men distraught, in search of some
lost treasure.

"'Young man,' cried the eunuch, 'have you seen the Queen's dog?'
Zadig answered modestly, 'A bitch, I think, not a dog.'
'Quite right,' replied the eunuch; and Zadig continued, 'A very
small spaniel who has lately had puppies; she limps with the
left foreleg, and has very long ears.' 'Ah! you have seen her
then,' said the breathless eunuch. 'No,' answered Zadig, 'I have
not seen her; and I really was not aware that the Queen
possessed a spaniel.'

"By an odd coincidence, at the very same time, the handsomest
horse in the King's stables broke away from his groom in the
Babylonian plain. The grand huntsman and all his staff were
seeking the horse with as much anxiety as the eunuch and his
people the spaniel; and the grand huntsman asked Zadig if he had
not seen the King's horse go that way.

"'A first-rate galloper, small-hoofed, five feet high;
tail three feet and a half long; cheek pieces of the bit of
twenty-three carat gold; shoes silver?' said Zadig.

"'Which way did he go? Where is he?' cried the grand huntsman.

"'I have not seen anything of the horse, and I never heard of
him before,' replied Zadig.

"The grand huntsman and the chief eunuch made sure that Zadig
had stolen both the King's horse and the Queen's spaniel, so
they haled him before the High Court of Desterham, which at once
condemned him to the knout, and transportation for life to
Siberia. But the sentence was hardly pronounced when the lost
horse and spaniel were found. So the judges were under the
painful necessity of reconsidering their decision: but they
fined Zadig four hundred ounces of gold for saying he had seen
that which he had not seen.

"The first thing was to pay the fine; afterwards Zadig was
permitted to open his defence to the court, which he did in the
following terms:

"'Stars of justice, abysses of knowledge, mirrors of truth,
whose gravity is as that of lead, whose inflexibility is as that
of iron, who rival the diamond in clearness, and possess no
little affinity with gold; since I am permitted to address your
august assembly, I swear by Ormuzd that I have never seen the
respectable lady dog of the Queen, nor beheld the sacrosanct
horse of the King of Kings.

"'This is what happened. I was taking a walk towards the little
wood near which I subsequently had the honour to meet the
venerable chief eunuch and the most illustrious grand huntsman.
I noticed the track of an animal in the sand, and it was easy to
see that it was that of a small dog. Long faint streaks upon the
little elevations of sand between the footmarks convinced me
that it was a she dog with pendent dugs, showing that she must
have had puppies not many days since. Other scrapings of the
sand, which always lay close to the marks of the forepaws,
indicated that she had very long ears; and, as the imprint of
one foot was always fainter than those of the other three, I
judged that the lady dog of our august Queen was, if I may
venture to say so, a little lame.

"'With respect to the horse of the King of Kings, permit me to
observe that, wandering through the paths which traverse the
wood, I noticed the marks of horse-shoes. They were all
equidistant. "Ah!" said I, "this is a famous galloper." In a
narrow alley, only seven feet wide, the dust upon the trunks of
the trees was a little disturbed at three feet and a half from
the middle of the path. "This horse," said I to myself, "had a
tail three feet and a half long, and, lashing it from one side
to the other, he has swept away the dust." Branches of the trees
met overhead at the height of five feet, and under them I saw
newly fallen leaves; so I knew that the horse had brushed some
of the branches, and was therefore five feet high. As to his
bit, it must have been made of twenty-three carat gold, for he
had rubbed it against a stone, which turned out to be a
touchstone, with the properties of which I am familiar by
experiment. Lastly, by the marks which his shoes left upon
pebbles of another kind, I was led to think that his shoes were
of fine silver.'

"All the judges admired Zadig's profound and subtle discernment;
and the fame of it reached even the King and the Queen. From the
ante-rooms to the presence-chamber, Zadig's name was in
everybody's mouth; and, although many of the magi were of
opinion that he ought to be burnt as a sorcerer, the King
commanded that the four hundred ounces of gold which he had been
fined should be restored to him. So the officers of the court
went in state with the four hundred ounces; only they retained
three hundred and ninety-eight for legal expenses, and their
servants expected fees."

Those who are interested in learning more of the fateful history
of Zadig must turn to the original; we are dealing with him only
as a philosopher, and this brief excerpt suffices for the
exemplification of the nature of his conclusions and of the
methods by which he arrived at them.

These conclusions may be said to be of the nature of
retrospective prophecies; though it is perhaps a little
hazardous to employ phraseology which perilously suggests a
contradiction in terms--the word "prophecy" being so constantly,
in ordinary use, restricted to "foretelling." Strictly, however,
the term prophecy applies as much to outspeaking as to
foretelling; and, even in the restricted sense of "divination,"
it is obvious that the essence of the prophetic operation does
not lie in its backward or forward relation to the course of
time, but in the fact that it is the apprehension of that which
lies out of the sphere of immediate knowledge; the seeing of
that which, to the natural sense of the seer, is invisible.

The foreteller asserts that, at some future time, a properly
situated observer will witness certain events; the clairvoyant
declares that, at this present time, certain things are to be
witnessed a thousand miles away; the retrospective prophet
(would that there were such a word as "backteller!") affirms
that, so many hours or years ago, such and such things were to
be seen. In all these cases, it is only the relation to time
which alters--the process of divination beyond the limits of
possible direct knowledge remains the same.

No doubt it was their instinctive recognition of the analogy
between Zadig's results and those obtained by authorised
inspiration which inspired the Babylonian magi with the desire
to burn the philosopher. Zadig admitted that he had never either
seen or heard of the horse of the king or of the spaniel of the
queen; and yet he ventured to assert in the most positive
manner that animals answering to their description did actually
exist and ran about the plains of Babylon. If his method was
good for the divination of the course of events ten hours old,
why should it not be good for those of ten years or ten
centuries past; nay, might it not extend ten thousand years and
justify the impious in meddling with the traditions of Oannes
and the fish, and all the sacred foundations of
Babylonian cosmogony?

But this was not the worst. There was another consideration
which obviously dictated to the more thoughtful of the magi the
propriety of burning Zadig out of hand. His defence was worse
than his offence. It showed that his mode of divination was
fraught with danger to magianism in general. Swollen with the
pride of human reason, he had ignored the established canons of
magian lore; and, trusting to what after all was mere carnal
common sense, he professed to lead men to a deeper insight into
nature than magian wisdom, with all its lofty antagonism to
everything common, had ever reached. What, in fact, lay at the
foundation of all Zadig's argument but the coarse commonplace
assumption, upon which every act of our daily lives is based,
that we may conclude from an effect to the pre-existence of a
cause competent to produce that effect?

The tracks were exactly like those which dogs and horses leave;
therefore they were the effects of such animals as causes.
The marks at the sides of the fore-prints of the dog track were
exactly such as would be produced by long trailing ears;
therefore the dog's long ears were the causes of these marks--
and so on. Nothing can be more hopelessly vulgar, more unlike
the majestic development of a system of grandly unintelligible
conclusions from sublimely inconceivable premisses such as
delights the magian heart. In fact, Zadig's method was nothing
but the method of all mankind. Retrospective prophecies, far
more astonishing for their minute accuracy than those of Zadig,
are familiar to those who have watched the daily life of
nomadic people.

From freshly broken twigs, crushed leaves, disturbed pebbles,
and imprints hardly discernible by the untrained eye, such
graduates in the University of Nature will divine, not only the
fact that a party has passed that way, but its strength, its
composition, the course it took, and the number of hours or days
which have elapsed since it passed. But they are able to do this
because, like Zadig, they perceive endless minute differences
where untrained eyes discern nothing; and because the
unconscious logic of common sense compels them to account for
these effects by the causes which they know to be competent to
produce them.

And such mere methodised savagery was to discover the hidden
things of nature better than a priori deductions from the
nature of Ormuzd--perhaps to give a history of the past, in
which Oannes would be altogether ignored! Decidedly it were
better to burn this man at once.

If instinct, or an unwonted use of reason, led Moabdar's magi to
this conclusion two or three thousand years ago, all that can be
said is that subsequent history has fully justified them.
For the rigorous application of Zadig's logic to the results of
accurate and long-continued observation has founded all those
sciences which have been termed historical or palaetiological,
because they are retrospectively prophetic and strive towards
the reconstruction in human imagination of events which have
vanished and ceased to be.

History, in the ordinary acceptation of the word, is based upon
the interpretation of documentary evidence; and documents would
have no evidential value unless historians were justified in
their assumption that they have come into existence by the
operation of causes similar to those of which documents are, in
our present experience, the effects. If a written history can be
produced otherwise than by human agency, or if the man who wrote
a given document was actuated by other than ordinary human
motives, such documents are of no more evidential value than so
many arabesques.

Archaeology, which takes up the thread of history beyond the
point at which documentary evidence fails us, could have no
existence, except for our well grounded confidence that
monuments and works of art or artifice, have never been produced
by causes different in kind from those to which they now owe
their origin. And geology, which traces back the course of
history beyond the limits of archaeology, could tell us nothing
except for the assumption that, millions of years ago, water,
heat, gravitation, friction, animal and vegetable life, caused
effects of the same kind as they now cause. Nay, even physical
astronomy, in so far as it takes us back to the uttermost point
of time which palaetiological science can reach, is founded upon
the same assumption. If the law of gravitation ever failed to be
true, even to a small extent, for that period, the calculations
of the astronomer have no application.

The power of prediction, of prospective prophecy, is that which
is commonly regarded as the great prerogative of physical
science. And truly it is a wonderful fact that one can go into a
shop and buy for a small price a book, the "Nautical Almanac,"
which will foretell the exact position to be occupied by one of
Jupiter's moons six months hence; nay, more, that, if it were
worth while, the Astronomer-Royal could furnish us with as
infallible a prediction applicable to 1980 or 2980.

But astronomy is not less remarkable for its power of
retrospective prophecy.

Thales, oldest of Greek philosophers, the dates of whose
birth and death are uncertain, but who flourished about 600
B.C., is said to have foretold an eclipse of the sun which took
place in his time during a battle between the Medes and the
Lydians. Sir George Airy has written a very learned and
interesting memoir<2> in which he proves that such an eclipse
was visible in Lydia on the afternoon of the 28th of May in the
year 585 B.C.

No one doubts that, on the day and at the hour mentioned by the
Astronomer-Royal, the people of Lydia saw the face of the sun
totally obscured. But, though we implicitly believe this
retrospective prophecy, it is incapable of verification. In the
total absence of historical records, it is impossible even to
conceive any means of ascertaining directly whether the eclipse
of Thales happened or not. All that can be said is, that the
prospective prophecies of the astronomer are always verified;
and that, inasmuch as his retrospective prophecies are the
result of following backwards, the very same method as that
which invariably leads to verified results, when it is worked
forwards, there is as much reason for placing full confidence in
the one as in the other. Retrospective prophecy is therefore a
legitimate function of astronomical science; and if it is
legitimate for one science it is legitimate for all;
the fundamental axiom on which it rests, the constancy of the
order of nature, being the common foundation of all scientific
thought. Indeed, if there can be grades in legitimacy, certain
branches of science have the advantage over astronomy, in so far
as their retrospective prophecies are not only susceptible of
verification, but are sometimes strikingly verified.

Such a science exists in that application of the principles of
biology to the interpretation of the animal and vegetable
remains imbedded in the rocks which compose the surface of the
globe, which is called Palaeontology.

At no very distant time, the question whether these so-called
"fossils," were really the remains of animals and plants was
hotly disputed. Very learned persons maintained that they were
nothing of the kind, but a sort of concretion, or
crystallisation, which had taken place within the stone in which
they are found; and which simulated the forms of animal and
vegetable life, just as frost on a window-pane imitates
vegetation. At the present day, it would probably be impossible
to find any sane advocate of this opinion; and the fact is
rather surprising, that among the people from whom the circle-
squarers, perpetual-motioners, flat-earthed men and the like,
are recruited, to say nothing of table-turners and spirit-
rappers, somebody has not perceived the easy avenue to
nonsensical notoriety open to any one who will take up the
good old doctrine, that fossils are all lusus naturae.

The position would be impregnable, inasmuch as it is quite
impossible to prove the contrary. If a man choose to maintain
that a fossil oyster shell, in spite of its correspondence, down
to every minutest particular, with that of an oyster fresh taken
out of the sea, was never tenanted by a living oyster, but is a
mineral concretion, there is no demonstrating his error.
All that can be done is to show him that, by a parity of
reasoning, he is bound to admit that a heap of oyster shells
outside a fishmonger's door may also be "sports of nature," and
that a mutton bone in a dust-bin may have had the like origin.
And when you cannot prove that people are wrong, but only that
they are absurd, the best course is to let them alone.

The whole fabric of palaeontology, in fact, falls to the ground
unless we admit the validity of Zadig's great principle, that
like effects imply like causes, and that the process of
reasoning from a shell, or a tooth, or a bone, to the nature of
the animal to which it belonged, rests absolutely on the
assumption that the likeness of this shell, or tooth, or bone,
to that of some animal with which we are already acquainted, is
such that we are justified in inferring a corresponding degree
of likeness in the rest of the two organisms. It is on this very
simple principle, and not upon imaginary laws of
physiological correlation, about which, in most cases, we know
nothing whatever, that the so-called restorations of the
palaeontologist are based.

Abundant illustrations of this truth will occur to every one who
is familiar with palaeontology; none is more suitable than the
case of the so-called Belemnites. In the early days of
the study of fossils, this name was given to certain elongated
stony bodies, ending at one extremity in a conical point, and
truncated at the other, which were commonly reputed to be
thunderbolts, and as such to have descended from the sky.
They are common enough in some parts of England; and, in the
condition in which they are ordinarily found, it might be
difficult to give satisfactory reasons for denying them to be
merely mineral bodies.

They appear, in fact, to consist of nothing but concentric
layers of carbonate of lime, disposed in subcrystalline fibres,
or prisms, perpendicular to the layers. Among a great number of
specimens of these Belemnites, however, it was soon observed
that some showed a conical cavity at the blunt end; and, in
still better preserved specimens, this cavity appeared to be
divided into chambers by delicate saucer-shaped partitions,
situated at regular intervals one above the other. Now there is
no mineral body which presents any structure comparable to this,
and the conclusion suggested itself that the Belemnites must be
the effects of causes other than those which are at work in
inorganic nature. On close examination, the saucer-shaped
partitions were proved to be all perforated at one point, and
the perforations being situated exactly in the same line, the
chambers were seen to be traversed by a canal, or
siphuncle, which thus connected the smallest or aphical
chamber with the largest. There is nothing like this in the
vegetable world; but an exactly corresponding structure is met
with in the shells of two kinds of existing animals, the pearly
Nautilus and the Spirula, and only in them. These
animals belong to the same division--the Cephalopoda--as
the cuttle-fish, the squid, and the octopus. But they are the
only existing members of the group which possess chambered,
siphunculated shells; and it is utterly impossible to trace any
physiological connection between the very peculiar structural
characters of a cephalopod and the presence of a chambered
shell. In fact, the squid has, instead of any such shell, a
horny "pen," the cuttlefish has the so-called "cuttle-bone," and
the octopus has no shell, or, at most, a mere rudiment of one.

Nevertheless, seeing that there is nothing in nature at all like
the chambered shell of the Belemnite, except the shells of the
Nautilus and of the Spirula, it was legitimate to
prophesy that the animal from which the fossil proceeded must
have belonged to the group of the Cephalopoda.
Nautilus and Spirula are both very rare animals,
but the progress of investigation brought to light the singular
fact, that, though each has the characteristic cephalopodous
organisation, it is very different from the other. The shell of
Nautilus is external, that of Spirula internal;
Nautilus has four gills, Spirula two;
Nautilus has multitudinous tentacles, Spirula has
only ten arms beset with horny-rimmed suckers; Spirula,
like the squids and cuttle-fishes, which it closely resembles,
has a bag of ink which it squirts out to cover its retreat when
alarmed; Nautilus has none.

No amount of physiological reasoning could enable any one to say
whether the animal which fabricated the Belemnite was more like
Nautilus, or more like Spirula. But the accidental
discovery of Belemnites in due connection with black elongated
masses which were: certainly fossilised ink-bags, inasmuch as
the ink could be ground up and used for painting as well as if
it were recent sepia, settled the question; and it became
perfectly safe to prophesy that the creature which fabricated
the Belemnite was a two-gilled cephalopod with suckers on its
arms, and with all the other essential features of our living
squids, cuttle-fishes, and Spirulae. The palaeontologist
was, by this time, able to speak as confidently about the animal
of the Belemnite, as Zadig was respecting the queen's spaniel.
He could give a very fair description of its external
appearance, and even enter pretty fully into the details of its
internal organisation, and yet could declare that neither he,
nor any one else, had ever seen one. And as the queen's spaniel
was found, so happily has the animal of the Belemnite; a few
exceptionally preserved specimens have been discovered, which
completely verify the retrospective prophecy of those who
interpreted the facts of the case by due application of the
method of Zadig.

These Belemnites flourished in prodigious abundance in the seas
of the mesozoic, or secondary, age of the world's geological
history; but no trace of them has been found in any of the
tertiary deposits, and they appear to have died out towards the
close of the mesozoic epoch. The method of Zadig, therefore,
applies in full force to the events of a period which is
immeasurably remote, which long preceded the origin of the most
conspicuous mountain masses of the present world, and the
deposition, at the bottom of the ocean, of the rocks which form
the greater part of the soil of our present continents.
The Euphrates itself, at the mouth of which Oannes landed, is a
thing of yesterday compared with a Belemnite; and even the
liberal chronology of magian cosmogony fixes the beginning of
the world only at a time when other applications of Zadig's
method afford convincing evidence that, could we have been there
to see, things would have looked very much as they do now.
Truly the magi were wise in their generation; they foresaw
rightly that this pestilent application of the principles of
common sense, inaugurated by Zadig, would be their ruin.

But it may be said that the method of Zadig, which is simple
reasoning from analogy, does not account for the most striking
feats of modern palaeontology--the reconstruction of entire
animals from a tooth or perhaps a fragment of a bone; and it may
be justly urged that Cuvier, the great master of this kind of
investigation, gave a very different account of the process
which yielded such remarkable results.

Cuvier is not the first man of ability who has failed to make
his own mental processes clear to himself, and he will not be
the last. The matter can be easily tested. Search the eight
volumes of the "Recherches sur les Ossemens Fossiles" from cover
to cover, and nothing but the application of the method of Zadig
will be found in the arguments by which a fragment of a skeleton
is made to reveal the characters of the animal to which
it belonged.

There is one well-known case which may represent all. It is an
excellent illustration of Cuvier's sagacity, and he evidently
takes some pride in telling his story about it. A split slab of
stone arrived from the quarries of Montmartre, the two halves of
which contained the greater part of the skeleton of a small
animal. On careful examinations of the characters of the teeth
and of the lower jaw, which happened to be exposed, Cuvier
assured himself that they presented such a very close
resemblance to the corresponding parts in the living opossums
that he at once assigned the fossil to that genus.

Now the opossums are unlike most mammals in that they possess
two bones attached to the fore part of the pelvis, which are
commonly called "marsupial bones." The name is a misnomer,
originally conferred because it was thought that these bones
have something to do with the support of the pouch, or
marsupium, with which some, but not all, of the opossums are
provided. As a matter of fact, they have nothing to do with the
support of the pouch, and they exist as much in those opossums
which have no pouches as in those which possess them. In truth,
no one knows what the use of these bones may be, nor has any
valid theory of their physiological import yet been suggested.
And if we have no knowledge of the physiological importance of
the bones themselves, it is obviously absurd to pretend that we
are able to give physiological reasons why the presence of these
bones is associated with certain peculiarities of the teeth and
of the jaws. If any one knows why four molar teeth and an
inflected angle of the jaw are very generally found along with
marsupial bones, he has not yet communicated that knowledge to
the world.

If, however, Zadig was right in concluding from the likeness of
the hoof-prints which he observed to be a horse's that the
creature which made them had a tail like that of a horse,
Cuvier, seeing that the teeth and jaw of his fossil were just
like those of an opossum, had the same right to conclude that
the pelvis would also be like an opossum's; and so strong was
his conviction that this retrospective prophecy, about an animal
which he had never seen before, and which had been dead and
buried for millions of years, would be verified, that he went to
work upon the slab which contained the pelvis in confident
expectation of finding and laying bare the "marsupial bones," to
the satisfaction of some persons whom he had invited to witness
their disinterment. As he says:--"Cette operation se fit en
presence de quelques personnes a qui j'en avais annonce d'avance
le resultat, dans l'intention de leur prouver par le fait la
justice de nos theories zoologiques; puisque le vrai cachet
d'une theorie est sans contredit la faculte qu'elle donne de
prevoir les phenomenes."

In the "Ossemens Fossiles" Cuvier leaves his paper just as it
first appeared in the "Annales du Museum," as "a curious
monument of the force of zoological laws and of the use which
may be made of them."

Zoological laws truly, but not physiological laws. If one sees a
live dog's head, it is extremely probable that a dog's tail is
not far off, though nobody can say why that sort of head and
that sort of tail go together; what physiological connection
there is between the two. So, in the case of the Montmartre
fossil, Cuvier, finding a thorough opossum's head, concluded
that the pelvis also would be like an opossum's. But, most
assuredly, the most advanced physiologist of the present day
could throw no light on the question why these are associated,
nor could pretend to affirm that the existence of the one is
necessarily connected with that of the other. In fact, had it so
happened that the pelvis of the fossil had been originally
exposed, while the head lay hidden, the presence of the
"marsupial bones," though very like an opossum's, would by no
means have warranted the prediction that the skull would turn
out to be that of the opossum. It might just as well have been
like that of some other marsupial; or even like that of the
totally different group of Monotremes, of which the only living
representatives are the Echidna and the

For all practical purposes, however, the empirical laws of co-
ordination of structures, which are embodied in the
generalisations of morphology, may be confidently trusted, if
employed with due caution, to lead to a just interpretation of
fossil remains; or, in other words, we may look for the
verification of the retrospective prophecies which are based
upon them.

And if this be the case, the late advances which have been
made in palaeontological discovery open out a new field for such
prophecies. For it has been ascertained with respect to many
groups of animals, that, as we trace them back in time, their
ancestors gradually cease to exhibit those special modifications
which at present characterise the type, and more nearly embody
the general plan of the group to which they belong.

Thus, in the well-known case of the horse, the toes which are
suppressed in the living horse are found to be more and more
complete in the older members of the group, until, at the bottom
of the Tertiary series of America, we find an equine animal
which has four toes in front and three behind. No remains of the
horse tribe are at present known from any Mesozoic deposit.
Yet who can doubt that, whenever a sufficiently extensive series
of lacustrine and fluviatile beds of that age becomes known, the
lineage which has been traced thus far will be continued by
equine quadrupeds with an increasing number of digits, until the
horse type merges in the five-toed form towards which these
gradations point?

But the argument which holds good for the horse, holds good, not
only for all mammals, but for the whole animal world. And as the
study of the pedigrees, or lines of evolution, to which, at
present, we have access, brings to light, as it assuredly will
do, the laws of that process, we shall be able to reason from
the facts with which the geological record furnishes us to those
which have hitherto remained, and many of which, perhaps, may
for ever remain, hidden. The same method of reasoning which
enables us, when furnished with a fragment of an extinct animal,
to prophesy the character which the whole organism exhibited,
will, sooner or later, enable us, when we know a few of the
later terms of a genealogical series, to predict the nature of
the earlier terms.

In no very distant future, the method of Zadig, applied to a
greater body of facts than the present generation is fortunate
enough to handle, will enable the biologist to reconstruct the
scheme of life from its beginning, and to speak as confidently
of the character of long extinct beings, no trace of which has
been preserved, as Zadig did of the queen's spaniel and the
king's horse. Let us hope that they may be better rewarded for
their toil and their sagacity than was the Babylonian
philosopher; for perhaps, by that time, the magi also may be
reckoned among the members of a forgotten Fauna, extinguished in
the struggle for existence against their great rival,
common sense.


(1) "Discours sur les revolutions de la surface du globe."
Recherches sur les Ossemens Fossiles, Ed. iv, t.i. p.185.]

(2) "On the Eclipses of Agathocles, Thales, and Xerxes,"
Philosophical Transactions, vol. cxliii.


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