causes, _i.e._, bulk, figure, and motion of parts.

_III.--Various Faculties of the Mind_

What perception is everyone will know better by reflecting on what he
does himself when he sees, hears, feels, etc., or thinks, than by any
discourse of mine. This is certain, that whatever alterations are made
in the body, if they reach not the mind, whatever impressions are made
on the outward parts, if they are not taken notice of within, there is
no perception.

We ought further to consider concerning perception, that the ideas we
receive by sensation are often in grown people altered by the judgment
without our taking any notice of it. When we set before our eyes a round
globe of any uniform colour--_e.g._, gold, alabaster, or jet--it is
certain that the idea thereby imprinted in our mind is of a flat circle
variously shadowed with several degrees of light and brightness coming
to our eyes. But we having by use been accustomed to perceive what kind
of appearances convex bodies are wont to make in us, what alterations
are made in the reflections of light by the difference of the sensible
figures of bodies, the judgment presently, by an habitual custom, alters
the appearances into their causes; so that from that which is truly a
variety of shadow or colour collecting the figure, it makes it pass for
a mark of figure, and frames to itself the perception of a convex figure
and a uniform colour, when the idea we receive from thence is only a
plane variously coloured, as is evident in painting. Perception, then,
is the first operation of our intellectual faculties, and the inlet of
all knowledge into our minds.

The next faculty of the mind whereby it makes a further progress towards
knowledge is that which I call Retention, or the keeping of those simple
ideas which from sensation or reflection it hath received. This is done,
first, by keeping the idea which is brought into it for some time
actually in view, which is called Contemplation. The other way of
retention is the power to revive again in our minds those ideas which
after imprinting have disappeared, or have been, as it were, laid aside
out of sight; and thus we do when we conceive heat or light, yellow or
sweet, the object being removed. This is memory, which is, as it were,
the storehouse of our ideas.

Another faculty we may take notice of in our minds is that of
Discerning, and distinguishing between the several ideas it has. It is
not enough to have a confused