_A._ Aristotle, I think, meaneth by body, _substance_, or _subjectum_, wherein colour, sound, and other fancies are, as he says, inherent. For the word essence has no affinity with substance. And Seneca says, he understands it not. And no wonder: for essence is no part of the language of mankind, but a word devised by philosophers out of the copulation of two names, as if a man having two hounds could make a third, if it were need, of their couples. _B._ It is just so. For having said in themselves, (for example): _a tree is a plant_, and conceiving well enough what is the signification of those names, knew not what to make of the word _is_, that couples those names; nor daring to call it a body, they called it by a new name (derived from the word _est_), _essentia_, and _substantia_, deceived by the idiom of their own language. For in many other tongues, and namely in the Hebrew, there is no such copulative. They thought the names of things sufficiently connected, when they are placed in their natural consequence; and were therefore never troubled with essences, nor other fallacy from the copulative _est_. ========== CHAPTER II. OF THE PRINCIPLES AND METHOD OF NATURAL PHILOSOPHY. _A._ This history of the old philosophers has not put me out of love, but out of hope of philosophy from any of their writings. I would therefore try if I could attain any knowledge therein by my own meditation: but I know neither where to begin, nor which way to proceed. _B._ Your desire, you say, is to know the causes of the effects or phenomena of nature; and you confess they are fancies, and, consequently, that they are in yourself; so that the causes you seek for only are without you, and now you would know how those external bodies work upon you to produce those phenomena. The beginning therefore of your enquiry ought to be at; _What it is you call a cause?_ I mean an efficient cause: for the philosophers make four kinds of causes, whereof the efficient is one. Another they call the formal cause, or simply the form or essence of the thing caused; as when they say, four equal angles and four equal sides are the cause of a square figure; or that heaviness is the cause that makes heavy bodies to descend; but that is not the cause you seek for, nor any thing but this: _It descends because it descends_. The third is the material cause, as when they say, the walls and roof, &c. of a house are the cause of a house. The fourth is the final cause, and hath place only in moral philosophy. _A._ We will think of final causes upon some other occasion; of formal and material not at all: I seek only the efficient, and how it acteth from the beginning to the production of the effect.