VI. And these are those three kinds which most people believe the Peripatetics speak of: and so far they are not wrong; for this division is the work of that school. But they are mistaken if they think that the Academicians—those at least who bore this name at that time—are different from the Peripatetics. The principle, and the chief good asserted by both appeared to be the same—namely, to attain those things which were in the first class by nature, and which were intrinsically desirable; the whole of them, if possible, or, at all events, the most important of them. But those are the most important which exist in the mind itself, and are conversant about virtue itself. Therefore, all that ancient philosophy perceived that a happy life was placed in virtue alone; and yet that it was not the happiest life possible, unless the good qualities of the body were added to it, and all the other things which have been already mentioned, which are serviceable towards acquiring a habit of virtue. From this definition of theirs, a certain principle of action in life, and of duty itself, was discovered, which consisted in the preservation of those things which nature might prescribe. Hence arose the avoidance of sloth, and contempt of pleasures; from which proceeded the willingness to encounter many and great labours and pains, for the sake of what was right and honourable, and of those things which are conformable to the objects of nature. Hence was generated friendship, and justice, and equity; and these things were preferred to pleasure and to many of the advantages of life. This was the system of morals recommended in their school, and the method and design of that division which I have placed first. But concerning nature (for that came next), they spoke in such a manner that they divided it into two parts,—making one efficient, and the other lending itself, as it were, to the first, as subject matter to be worked upon. For that part which was efficient they thought there was power; and in that which was made something by it they thought there was some matter; and something of both in each. For they considered that matter itself could have no cohesion, unless it were held together by some power; and that power could have none without some matter to work upon; for that is nothing which is not necessarily somewhere. But that which exists from a combination of the two they called at once body, and a sort of quality, as it were. For you will give me leave, in speaking of subjects which have not previously been in fashion, to use at times words which have never been heard of (which, indeed, is no more than the Greeks themselves do, who have been long in the habit of discussing these subjects).