ock, or a wall, at a distance from
sufficient soil and moisture, it husbands its scanty means, and sends
down from its elevation an extra root to the ground, to collect
additional nourishment where it is to be had.

In every department of animal life, also, the principle appears to
exist, and exhibits itself in the conduct of all free agents, from the
insect to the elephant. The dog that has been kindly treated in a
particular house, seldom fails to visit it again; and when he is
violently driven from another, the same principle indisposes him to
return. It is upon record, that a surgeon who had bandaged the broken
leg of a dog, was afterwards visited by his patient, who brought
another, requiring a similar operation. The horse, in like manner, is
proverbially sagacious in the application of his knowledge.
Mismanagement in a groom in one instance, may create a "vice," which may
lessen his value during life. This "vice," which is confirmed by
practice, is nothing more than the repeated application of his
knowledge. Such a "vice," accordingly, is best cured by avoiding the
circumstances which originally gave rise to it, till it dies from his
memory. Many other instances of a similar kind in the lower animals will
readily occur to the reader, all of which lead directly to the
conclusion, that, even in the brute creation, Nature not only prompts
them to collect information from what happens around them, and to act in
correspondence to its indications; but that, in fact, all the knowledge
they receive, or are capable of acquiring above instinct, is retained or
lost, exactly in proportion as it is, or is not, put to use.

In the case of rational creatures, this great design of Nature is still
more distinctly marked,--is intended for more important purposes,--and
is carried on by a separate system of internal machinery, part of which
at least is peculiar to man. This system of mental machinery consists of
two kinds, one of which may, we think, with propriety get the popular
name of the "Animal, or Common Sense," and the other has already
received the appropriate name of "The Moral Sense," or conscience. To
Nature's method of using these principles, for prompting and directing
us in the use of our knowledge, we shall now shortly advert.

CHAP. IX.

_On Nature's Methods of Applying Knowledge by the Principle of the
Animal, or Common Sense._

When an infant, by laying hold of a hot tea-pot burns its hand, it
refuses