PHIL. As for the rational deducing of causes from effects, that is beside our inquiry. And, by the senses you can best tell whether you perceive anything which is not immediately perceived. And I ask you, whether the things immediately perceived are other than your own sensations or ideas? You have indeed more than once, in the course of this conversation, declared yourself on those points; but you seem, by this last question, to have departed from what you then thought.
HYL. To speak the truth, Philonous, I think there are two kinds of objects:—the one perceived immediately, which are likewise called IDEAS; the other are real things or external objects, perceived by the mediation of ideas, which are their images and representations. Now, I own ideas do not exist without the mind; but the latter sort of objects do. I am sorry I did not think of this distinction sooner; it would probably have cut short your discourse.
PHIL. Are those external objects perceived by sense or by some other faculty?
HYL. They are perceived by sense.
PHIL. Howl Is there any thing perceived by sense which is not immediately perceived?
HYL. Yes, Philonous, in some sort there is. For example, when I look on a picture or statue of Julius Caesar, I may be said after a manner to perceive him (though not immediately) by my senses.
PHIL. It seems then you will have our ideas, which alone are immediately perceived, to be pictures of external things: and that these also are perceived by sense, inasmuch as they have a conformity or resemblance to our ideas?
HYL. That is my meaning.
PHIL. And, in the same way that Julius Caesar, in himself invisible, is nevertheless perceived by sight; real things, in themselves imperceptible, are perceived by sense.
HYL. In the very same.