ersed through air, or carried off by
water, to form new combinations, and afford food for other
animals.

The human body has been defined to be a machine composed of bones
and muscles, with their proper appendages, for the purpose of
motion, at the instance of its intelligent principle. From this
principle, nerves, or instruments of sensation, are likewise
detached to the various parts of the body, for such information as
may be necessary to determine it to those motions of the body,
which may conduce to the happiness of the former, and the
preservation of both.

It may perhaps be objected to this definition, that the body
consists of other parts besides bones, muscles, and nerves; this
is undoubtedly true; but, if we examine more minutely, we shall
find that all the other parts, as well as functions of the body,
seem only to be subservient to the purposes I have mentioned. For,
in the first place, the muscles which are necessary to the motions
of the body, are, from the nature of their constitution, subject
to continual waste; to repair which waste, some of the other
functions have been contrived.

Secondly, most of the other parts and functions of the body, are
either necessary to the action of the muscles, or to the operation
of the intelligent principle, or both.

Lastly, from the sensibility, and delicate structure, of the
muscles and nerves, they require to be defended from external
injuries: this is done by membranes, and other contrivances,
fitted for the purpose.

To see this more clearly, we shall examine a little more
particularly how each of the functions is subservient to the
muscular and nervous systems. For this purpose it may be observed,
1st. that the stomach and digestive faculties serve to assimilate
the food, or convert it into matter proper to repair the continual
waste of solids and fluids. The circulation of the blood besides
being absolutely necessary, as we shall afterwards see, to the
action of the muscles, distributes the nourishment, thus
assimilated and prepared by the stomach, to all parts of the body.
The different glands separate liquors from the blood, for useful,
but still for subservient purposes. Thus the salivary glands,
stomach, pancreas, and liver, separate juices necessary to the
proper digestion and assimilation of the food. The kidneys serve
to strain off from the blood the useless and superfluous water,
salts, &c. which if allowed to remain in the body would be very
i