For I am convinced that these two natural laws, which are the simplest of all namely, that motion occurs or tends to occur in a straight line, and that the impact of bodies is communicated in proportion to, and along the line of, their pressureare sufficient, if the first instances of motion are wisely distributed, to produce the world such as we see it,.e., the sky, the stars, the planets, the comets, earth and water, air and fire, in a word, the elements of all bodies that are not organized or living; for organized bodies depend on the initial construction of those of which they are born, and it is likely that they were formed at the creation of the world, though not as they appear to our eyes, and that with time they receive nothing more than the growth necessary to become visible.