BOOK II
Chapter 1
The subjects of investigation are equal in number to the things which we scientifically know; but we investigate four things; that a thing is, why it is, if it is, what it is. For when we inquire whether it is this, or that, having reference to a number (as whether the sun is eclipsed or not) we investigate the that, and a sign of this is that when we have found that it is eclipsed we desist from our inquiries, and if we knew from the first that it is eclipsed, we do not inquire whether it is so. But when we know the that, we investigate the why, for instance, when we know that there is an eclipse, and there is an earthquake, we inquire why there is an eclipse, and an earthquake. These things indeed we investigate thus, but some after another manner, for instance, if there is, or is not, a centaur or a God. I say if there is or is not, simply, and not if it is white or not. When however we know that a thing is, we inquire what it is, for instance, what God, or what man is.
Chapter 2
The things then which we investigate, and which having discovered we know, are such and so many, but when we inquire the that or if a thing
