And again, you must not demand the reason either in all things alike,[21] because in some it is sufficient that the fact has been well demonstrated, which is the case with first principles; and the fact is the first step, _i.e._ starting-point or principle. And of these first principles some are obtained by induction, some by perception,[22] some by a course of habituation, others in other different ways. And we must try to trace up each in their own nature, and take pains to secure their being well defined, because they have great influence on what follows: it is thought, I mean, that the starting-point or principle is more than half the whole matter, and that many of the points of enquiry come simultaneously into view thereby. Chapter VI. We must now enquire concerning Happiness, not only from our conclusion and the data on which our reasoning proceeds, but likewise from what is commonly said about it: because with what is true all things which really are are in harmony, but with that which is false the true very soon jars. Now there is a common division of goods into three classes; one being called external, the other two those of the soul and body respectively, and those belonging to the soul we call most properly and specially good. Well, in our definition we assume that the actions and workings of the soul constitute Happiness, and these of course belong to the soul. And so our account is a good one, at least according to this opinion, which is of ancient date, and accepted by those who profess philosophy. Rightly too are certain actions and workings said to be the end, for thus it is brought into the number of the goods of the soul instead of the external. Agreeing also with our definition is the common notion, that the happy man lives well and does well, for it has been stated by us to be pretty much a kind of living well and doing well. And further, the points required in Happiness are found in combination in our account of it. For some think it is virtue, others practical wisdom, others a kind of scientific philosophy; others that it is these, or else some one of them, in combination with pleasure, or at least not independently of it; while others again take in external prosperity. Of these opinions, some rest on the authority of numbers or antiquity, others on that of few, and those men of note: and it is not likely that either of these classes should be wrong in all points, but be right at least in some one, or even in most. Now with those who assert it to be Virtue (Excellence), or some kind of Virtue, our account agrees: for working in the way of Excellence surely belongs to Excellence.