ciples, if what is to be demonstrated is inherent in a subject so far as the subject is that (which it is) to have a scientific knowledge of that thing is not this, it it should be demonstrated from true, indemonstrable, and immediate (propositions). For we may so demonstrate possibly, as Bryso did, the quadrature of the circle, since such reasonings prove through something common, that which is inherent in another thing, hence these arguments are adapted to other things not of the same genus. Wherefore that thing would not be scientifically known, as far as it is such, but from accident, for otherwise the demonstration would not be adapted also to another genus.
We know however each thing not accidentally when we know it according to that, after which it is inherent from principles which are those of that thing, so far as it is that thing; as that a thing has angles equal to two right angles, in which the thing spoken of is essentially inherent from the principles of this thing. Hence if that is essentially inherent in what it is inherent, it is necessary that the middle should be in the same affinity, but if not, yet it will be as harmonics are proved through an arithmetical principle. Such things however are demonstrated after a similar manner,
