Vitae philosophorum

Hence, since such a course is of service to all who take up natural science, I, who devote to the subject my continuous energy and reap the calm enjoyment of a life like this, have prepared for you just such an epitome and manual of the doctrines as a whole.

In the first place, Herodotus, you must understand what it is that words denote, in order that by reference to this we may be in a position to test opinions, inquiries, or problems, so that our proofs may not run on untested ad infinitum, nor the terms we use be empty of meaning.

For the primary signification of every term employed must be clearly seen, and ought to need no proving[*](Epicurus explains this more fully in Fr. 258 (Usener, p. 189). For proof and proving Bignone substitutes declaration and declare.); this being necessary, if we are to have something to which the point at issue or the problem or the opinion before us can be referred.

Next, we must by all means stick to our sensations, that is, simply to the present impressions whether of the mind or of any criterion whatever, and similarly to our actual feelings, in order that we may have the means of determining that which needs confirmation and that which is obscure.

When this is clearly understood, it is time to consider generally things which are obscure. To begin with, nothing comes into being out of what is non-existent.[*](This is no innovation of Epicurus but a tenet common to all the pre-Socratics: the One, or Nature as a whole, assumed by the Ionians, is unchangeable in respect of generation and destruction; cf. Aristotle, Met. i. 3. 984 a 31. The pluralists were naturally even more explicit: see the wellknown fragments, Anax. 17 d, Emped. 8 d. Lucretius (i. 180 f.) expands the doctrine.) For in that case anything would have arisen out of anything, standing as it would in no need of its proper germs.[*](Cf.§§ 41, 54. Lucr. i. 125 f. is the best commentary.)