Note 18 — Chapter XXVIII · THEÆTETUS.

In regard to the impossibility of carrying abstraction so far as to discard the thinking subject, see Hobbes, Computation or Logic, ch. vii. 1.

“In the teaching of natural philosophy I cannot begin better than from privation; that is, from feigning the world to be annihilated. But if such annihilation of all things be supposed, it may perhaps be asked what would remain for any man (whom only I except from this universal annihilation of things) to consider as the subject of philosophy, or at all to reason upon; or what to give names unto for ratiocination’s sake.

“I say, therefore, there would remain to that man ideas of the world, and of all such bodies as he had, before their annihilation, seen with his eyes, or perceived by any other sense; that is to say, the memory and imagination of magnitudes, motions, sounds, colours, &c., as also of their order and parts. All which things, though they be nothing but ideas and phantasms, happening internally to him that imagineth, yet they will appear as if they were external and not at all depending upon any power of the mind. And these are the things to which he would give names and subtract them from, and compound them with one another. For seeing that after the destruction of all other things I suppose man still remaining, and namely that he thinks, imagines, and remembers, there can be nothing for him to think of but what is past.… Now things may be considered, that is, be brought into account, either as internal accidents of our mind, in which manner we consider them when the question is about some faculty of the mind: or, as species of external things, not as really existing, but appearing only to exist, or to have a being without us. And in this manner we are now to consider them.”