Appendix 28.

(806) [Idea relative to subsistence of things]

I take the opportunity of resolving a possible doubt about the distinction between an idea and judgment on the subsistence of things. I said (cf. 398-401) that any object whatsoever could be mentally conceived as endowed with all its essential and accidental characteristics, and still not subsist. Judgment of its subsistence, therefore, adds nothing to the idea we have of it. But are not place and time characteristics of a thing, and added to it when we judge that the thing subsists? If so, the judgment does add something that was not previously present in the idea of the thing.

I would deny that place and time are characteristics of a thing. Wherever and whenever a thing subsists, it is always itself, neither more nor less. There is no change, no addition to its nature. This needs careful consideration, and proof of it may be found in experience undergone by sensitive entia transported thousands of miles without feeling the change. This occurs because being in one place or another (and the same may be said about time) has no effect on their nature which remains exactly what it was. Place and time do not enter, therefore, into the idea of a thing.

When, however, judgment on the subsistence of a corporeal thing depends upon sense perception, such judgment determines its place. If I perceive a body with my senses, I must perceive it in a determined place. But what is this place occupied by the perceived body? Place, we maintain, is something appertaining to reality precisely because it is foreign to the idea but at home in the judgment together with the subsistence of the thing of which, in corporeal matters, it forms an element.

An immediate objection springs to mind: what of the idea of place? It is of course true that we have such an idea, but in the same way as we have the idea of subsistence which, like all other ideas, is universal because it is only the possibility that an ens subsists. Where, however, we are dealing with the particular subsistence of an ens, the subsistence we think of is the idea of subsistence focused through a judgment on an individual. The same is true about our idea of a place. This idea is the possibility that an extended ens exists in that place. But when we perceive a subsistent, extended ens, we determine the idea of that extended thing by a judgment affirming its subsistence and, together with its subsistence, the place it occupies. The difference between subsistence and place is that the former is the act itself of the ens while place is an abstract, that is, the mode of the subsistence of the ens we call body.

The distinction between the content of an idea or essence and the judgment which makes known something about it (the particular subsistence), was known to early philosophers, but often forgotten (it is in fact very difficult to keep before the mind). As a result, questions insoluble without it were tackled by means of other distinctions resembling it. This resulted in serious embarrassment for science by multipying entia without necessity under the guise of such distinctions. One of these distinctions, which we have already mentioned, is that between general and particular matter. It was thought that the former, but not the latter, was necessary for corporeal things. In fact, it is not true that these two kinds of matter exist. What exists is: 1. particular matter; and 2. the idea of particular matter. The latter is simply particular matter in so far as it is thought possible. Because what is possible is universal, it seems to be universal matter. The same kind of distinction was made by early philosophers between universal and particular quantity, and here too the same observation is relevant: universal quantity is only the idea of quantity.

The term intelligible quantity used by these philosophers shows they had some notion of this. In book 4 of Aristotle's Physics, Simplicius says: 'I think it is better to say that we have a specific extension' (the Greek has kat^eµdov, that is, 'according to the idea', as I have been suggesting) 'which can be seen in exemplars, and another extension conceived mentally by passive discernment of an indivisible substance without parts.' Intelligible quantity is that described as according to the idea, which is seen in exemplars, that is, in first ideas. It is therefore the idea of quantity, or, if you prefer, the quantity thought in the idea, which is the same as possible or universal quantity.