THOUGHTS ON THE NATURE OF THINGS. I. On the Division of Bodies, Continuity, and Vacuity. THE doctrine of Democritus concerning atoms is either true or useful for demonstration. For it is not easy either to grasp in thought or to express in words the genuine subtlety of nature, such as it is found in things, without supposing an atom. Now the word atom is used in two senses, not very different from one another. For it is either taken for the last term or smallest portion of the division or fraction of bodies, or else for a body without vacuity. With respect to the first, these two positions may be safely and certainly laid down; the one, that there is in things a much more subtle distribution and comminution than falls under view; the other, that this is not however infinite nor perpetually divisible. For if a man observe diligently, he will find that the minute particles of things in continued bodies are far more subtle than those in bodies broken and discontinued. For we see that a little saffron infused and stirred up in water will colour a whole hogshead, so as to make it distinguishable even by the sight from pure water. Now this distribution of saffron in the water is certainly more subtle than that of the finest powder, as will be shown if a similar quantity of powder of Brazil-wood, pomegranate flowers, or any highly coloured substance, which has not the sequacity of saffron to spread in liquids and incorporate itself with them, be infused in the same way. It was ridiculous therefore to take those small bodies that appear in the sun's rays for atoms. For these are like dust; whereas an atom, as Democritus himself said, no one ever saw or can see. But this distribution of things is shown much more wonderfully in smells. For if a little saffron will tinge and infect a whole hogshead of water with colour, a little civet will infect a suite of two or three large rooms with its odour. And let no one imagine that odours are diffused, like light or like heat and cold, without communication of substance; since he may observe that odours adhere even to solid bodies, as woods and metals, and that for no short time; also that by rubbing and washing they may be dispersed again and cleared away. But in these and similar things, no man in his senses will assert that the process is infinite, seeing this distribution or diffusion is confined to certain spaces, limits, and quantities of bodies; as is most manifestly shown in the above examples. With respect to the second sense of the word atom, namely, that it presupposes a vacuum, and defines an atom as that which is without a vacuum, it was a good and earnest diligence on the part of Hero to deny the existence of a collected vacuum, but maintain that of a vacuum interspersed. For when he saw the constant connection of bodies, and that no space at all could be found or assigned where a body was not; and much more, when he observed that heavy and ponderous bodies are carried upwards, and throw aside and violate their natures, rather than suffer an absolute separation from the body contiguous to them, he laid it down as certain that Nature abhorred any large or collected vacuum. On the other hand, when he perceived that the same matter of a body was contracted and condensed, and again expanded and dilated, and that it occupied and filed unequal spaces, sometimes larger and sometimes smaller, he did not see how this ingress and egress of bodies in their own places could happen except by means of a vacuum interspersed; less when the body was compressed, and more when it was relaxed. For this contraction must needs happen in one of these three ways; either in that just mentioned, namely, by the exclusion of vacuum in proportion to the contraction; or by the forcing out of some other body previously intermixed; or by some natural (whatever that may be) condensation and rarefaction of bodies. Now with regard to the forcing out of a finer body, that process seems to have no end. It is true indeed that sponges and the like porous bodies are contracted when the air is squeezed out; but it is shown by many experiments that the air itself admits of a considerable contraction. Are we then to suppose that the finer part of the air is squeezed out, and out of that part another, and so on for ever? Such an opinion is strongly opposed by the fact that the finer bodies are, |