kind, we shall find that they may be
affected in a still greater number of ways without changing their
actuality. We may easily proceed thus to infinity, and conceive
the whole of nature as one individual, whose parts, that is, all
bodies, vary in infinite ways, without any change in the
individual as a whole. I should feel bound to explain and
demonstrate this point at more length, if I were writing a
special treatise on body. But I have already said that such is
not my object; I have only touched on the question, because it
enables me to prove easily that which I have in view.

POSTULATES

I. The human body is composed of a number of individual
parts, of diverse nature, each one of which is in itself
extremely complex.

II. Of the individual parts composing the human body some
are fluid, some soft, some hard.

III. The individual parts composing the human body, and
consequently the human body itself, are affected in a variety of
ways by external bodies.

IV. The human body stands in need for its preservation of a
number of other bodies, by which it is continually, so to speak,
regenerated.

V. When the fluid part of the human body is determined by an
external body to impinge often on another soft part, it changes
the surface of the latter, and, as it were, leaves the impression
thereupon of the external body which impels it.

VI. The human body can move external bodies, and arrange
them in a variety of ways.

PROP. XIV. The human mind is capable of perceiving a great
number of things, and is so in proportion as its body is capable
of receiving a great number of impressions.

Proof.--The human body (by Post. iii. and vi.) is affected in
very many ways by external bodies, and is capable in very many
ways of affecting external bodies. But (II. xii.) the human
mind must perceive all that takes place in the human body; the
human mind is, therefore, capable of perceiving a great number of
things, and is so in proportion, &c. Q.E.D.

PROP. XV. The idea, which constitutes the actual being of the
human mind, is not simple, but compounded of a great number of
ideas.

Proof.--The idea constituting the actual being of the human
mind is the idea of the body (II. xiii.), which (Post. i.) is
composed of a great number of complex individual parts. But
there is necessarily in God the idea of each individual part
whereof the body is composed (II. viii. Coroll.); therefore
(II. vii.), the idea of the hu