160 
some respects, which yet differ in others. Or, in 
respect to the process of thought, that sort of 
reasoning by which we argue from known to un- 
known resemblances. 
The second law of philosophizing laid down by 
Sir Isaac Newton, recommends drawing conclu- 
sions from analogy where the resemblance be- 
tween the things compared is strong. “ Of nat- 
ural effects of the same kind,” says that law, 
“the same causes are to be assigned as far as it 
can be done. As of respiration in a man and in 
a beast; of the descent of stones in Europe and 
in America; of light in a culinary fire and in the 
sun; and of the reflection of light in the various 
planets.” Where the analogy is so very mani- 
fest as in the cases here adduced, the conclusion 
drawn from it approaches to absolute certainty ; 
and, in many cases, we have no better way of 
reasoning from what is known to what is un- 
known. The arguments by which Sir Isaac 
Newton establishes the truth of the system of 
universal gravitation are precisely of this sort. 
He proves that the planets, in their deflections 
towards the sun, are all governed by the same 
analogy that is observable in the deflections of 
the earth towards the sun, and of the moon to- 
-wards the earth, as well as of a body projected 
obliquely at the earth’s surface towards its cen- 
tre: whence he infers, with the force of demon- 
stration, that all these deflections spring from 
the same cause, or are governed by one and the 
same law, to wit, the power of gravitation, by 
which a heavy body, when unsupported, natu- 
rally falls to the ground. 
But there is a natural proneness in men to 
carry arguments drawn from analogy too far; so 
that this law of philosophizing requires to be in- 
terpreted with more strictness, and its abuses 
more carefully guarded against than any other. 
That principle of human thought by which we 
form numerous combinations among the objects 
of our knowledge, according to real or supposed 
resemblances, is continually prompting us to 
carry comparison farther than the nature of 
things will warrant. Weare always apt to judge 
of things little known by those with which we 
are familiar; and ‘to trace similitudes, which, 
though often the mere suggestions of our imagi- 
nation, we are apt to mistake for discoveries of 
reason. Natural historians are fond of tracing 
an analogy between the three kingdoms of na- 
ture,—the animal, the vegetable, and the mineral. 
The analogy between animals and vegetables is 
doubtless, in many cases, very striking. They 
are both of an organized or vascular structure; 
both grow and expand from minute germs by 
assimilating nourishment from the different ele- 
ments; both are capable of reproducing their 
kinds by the generation of ova or seeds. These, 
and various other points of analogy between 
plants and animals, are sufficiently striking, and 
have been admitted by all: see our article Ant- 
But naturalists have not stopped here: 
MALS. 
ANALOGY. 
they have extended to vegetables properties which 
can only belong to sentient beings. It is thus 
that they have ascribed to plants, a state of sleep 
and of wakefulness, a power of voluntary motion, 
and a capacity of avoiding danger, till at length 
they have not hesitated to ascribe to them ac- 
tual sensibility and perception, and have elevated 
them tothe very rank of living creatures. “Trees,” 
says Mr. White, “are animated; they have their 
food, their enjoyments, their grief, their health, 
their illness, their watcliing, their sleep, their 
emanations, their absorptions, their infancy, their 
growth, their puberty, their manhood, and their 
love. The man who does not find in animals 
younger brothers, and in plants cousins, more or 
less removed, is unacquainted with his own na- 
ture, and is devoid of the elements of morality.” 
[On the Gradations in Man, p. 6.| This is a con- 
siderable stretch of analogy; but it is exceed- 
ed by that spirit of generalization which would 
ascribe life and sensibility to stones. “ The 
vegetation of stones,” says the bishop of Llan- 
daff, “hath been admitted by many; and some 
have contended that minerals, as well as animals 
and vegetables, spring from seed; the greatest 
being nothing but the expansion of the parts of 
a minute grain of sand.” “Ido not know,” adds 
he, “whether it would be a very extravagant 
conjecture, which should suppose that all matter 
is, or has been, organized, enlivened, and ani- 
mated.” [Watson’s Chemical Essays, vol. v.] 
We infer from analogy, with a high degree of 
probability, that the planets are peopled. with 
inhabitants, on account of their numerous points 
of resemblance with our earth. They all revolve 
round the sun as the earth does, and are gov- 
erned in their revolution by the same law of 
gravitation. They all, like the earth, borrow 
their light from the sun, and most of them are 
known to have a rotation on their axes; and 
therefore, like the earth, to have a vicissitude of 
day and night. Several of them likewise are 
attended by moons as the earth is. From these 
manifold points of resemblance, it is highly rea- 
sonable to conclude that these bodies are, like 
our earth, destined to be the habitation of vari- 
ous orders of living creatures. Such an argu- 
ment, drawn from analogy, is perfectly legiti- 
mate, and carries with it the greatest probability. 
But who can help smiling at the extent to which 
the learned Wolfius carries this kind of analogi- 
cal reasoning, when he proceeds upon it to cal- 
culate the precise dimensions of the supposed 
inhabitants of the different planets! [Hlem. As- 
tron. Genev. 1735, part 2d.] The inhabitants of 
Jupiter, he thinks, must be giants; and he 
grounds his opinion chiefly on the small degree 
of solar light which they enjoy; so that the 
pupils of their eyes, and consequently their whole 
bodies, must be considerably larger than ours. 
Analogy between the whole animal kingdom 
and the whole vegetable kingdom, or between 
certain groups or species of animals and certain 
