otherwise how could it occasionally give motion to the limbs of
animals?--or be itself stimulated into motion by the obtrusions of
surrounding bodies, as of light, or odour?

If the spirit of animation was always necessarily penetrable, it could not
influence or be influenced by the solidity of common matter; they would
exist together, but could not detrude each other from the part of space,
where they exist; that is, they could not communicate motion to each other.
_No two things can influence or affect each other, which have not some
property common to both of them_; for to influence or affect another body
is to give or communicate some property to it, that it had not before; but
how can one body give that to another, which it does not possess
itself?--The words imply, that they must agree in having the power or
faculty of possessing some common property. Thus if one body removes
another from the part of space, that it possesses, it must have the power
of occupying that space itself: and if one body communicates heat or motion
to another, it follows, that they have alike the property of possessing
heat or motion.

Hence the spirit of animation at the time it communicates or receives
motion from solid bodies, must itself possess some property of solidity.
And in consequence at the time it receives other kinds of motion from
light, it must possess that property, which light possesses, to communicate
that kind of motion; and for which no language has a name, unless it may be
termed Visibility. And at the time it is stimulated into other kinds of
animal motion by the particles of sapid and odorous bodies affecting the
senses of taste and smell, it must resemble these particles of flavour, and
of odour, in possessing some similar or correspondent property; and for
which language has no name, unless we may use the words Saporosity and
Odorosity for those common properties, which are possessed by our organs of