15in mathematica fieri solet ceterisque etiam disciplinis, praeposui terminos regulasque quibus cuncta quae sequuntur efficiam.
I. Communis animi conceptio est enuntiatio quam quisque probat auditam. Harum duplex modus est. 20 Nam una ita communis est, ut omnium sit hominum, veluti si hanc proponas: “Si duobus aequalibus aequalia auferas, quae relinquantur aequalia esse,” nullus id intellegens neget. Alia vero est doctorum tantum, quae tamen ex talibus communibus animi 25 conceptionibus venit, ut est: “Quae incorporalia sunt, in loco non esse,” et cetera; quae non vulgus sed docti comprobant.
II. Diversum est esse et id quod est; ipsum enim esse nondum est, at vero quod est accepta essendi 30 forma est atque consistit.
III. Quod est participare aliquo potest, sed ipsum esse nullo modo aliquo participat. Fit enim participatio cum aliquid iam est; est autem aliquid, cum esse susceperit.
35 IV. Id quod est habere aliquid praeterquam quod ipsum est potest; ipsum vero esse nihil aliud praeter se habet admixtum.
V. Diversum est tantum esse aliquid et esse aliquid in eo quod est; illic enim accidens hic 40 substantia significatur.
therefore followed the example of the mathematicala and cognate sciences and laid down bounds and rules according to which I shall develop all that follows.
I. A common conception of the mind is a statement which anyone accepts as soon as he hears it. Of these there are two kinds. For one is common in that all men possess it; as, for instance, if you say, “If you take equals from two equals, the remainders are equal.” Nobody who grasps that would deny it. But the other kind is intelligible only to the learned, though it is derived from the same class of common conceptions; as “Things which are incorporeal are not in space,” and the like; these conceptions are approved as obvious to the learned but not to the common herd.
III. What is, can participate in something, but simple being does not participate in any way in anything. For participation is effected when something already is; but something is, when it has acquired being.
IV. That which is can possess something besides what it is itself. But simple being has no admixture of aught besides itself.
V. Merely to be something and to be something in virtue of existence are different; the former signifies an accident, the latter a substance.