12. Simple ideas, ektupa, and adequate.
Thus the mind has three sorts of abstract ideas or nominal essences:
First, simple ideas, which are ἔκτυπα or copies; but yet certainly adequate. Because, being intended to express
nothing but the power in things to produce in the mind such a sensation, that sensation when it is produced, cannot
but be the effect of that power. So the paper I write on, having the power in the light (I speak according to the
common notion of light) to produce in men the sensation which I call white, it cannot but be the effect of such a
power in something without the mind; since the mind has not the power to produce any such idea in itself: and
being meant for nothing else but the effect of such a power, that simple idea is real and adequate; the sensation of
white, in my mind, being the effect of that power which is in the paper to produce it, is perfectly adequate to that
power; or else that power would produce a different idea.
