2Thales thought that water was the first principle of all things. Heraclitus, the Ephesian, who, on account of the obscurity of his writings, was called σκοτεινὸς by the Greeks, maintained a similar doctrine in respect of fire. Democritus, and his follower Epicurus, held similar opinions with regard to atoms; by which term is understood such bodies as are incapable of being cut asunder, or, as some say, of further division. To water and fire the philosophy of the Pythagoreans added air and earth. Hence Democritus, though loosely expressing himself, seems to have meant the same thing, when he calls the elements indivisible bodies; for when he considers them incapable of corruption or alteration, and of eternal duration and infinite solidity, his hypothesis makes the particles not yet so connected as to form a body.
2First of all Thales thought that water was the primordial substance of all things. Heraclitus of Ephesus, surnamed by the Greeks σκοτεινος on account of the obscurity of his writings, thought that it was fire. Democritus and his follower Epicurus thought that it was the atoms, termed by our writers “bodies that cannot be cut up,” or, by some, “indivisibles.” The school of the Pythagoreans added air and the earthy to the water and fire. Hence, although Democritus did not in a strict sense name them, but spoke only of indivisible bodies, yet he seems to have meant these same elements, because when taken by themselves they cannot be harmed, nor are they susceptible of dissolution, nor can they be cut up into parts, but throughout time eternal they forever retain an infinite solidity.