Let us now go to the letter:
Epicurus to Herodotus, Wishing He May Do Well
For those, O Herodotus, who are not able accurately to comprehend all the things which I have written about nature, nor to investigate those larger books which I have composed on the subject, I have made an abridgment of the whole discussion on this question, as far as I thought sufficient to enable them to recollect accurately the most fundamental points; that so, on all grave occasions, they might be able to assist themselves on the most important and undeniable principles; in proportion as they devoted themselves to speculations on natural philosophy. And here it is necessary for those who have made sufficient progress in their view of the general question, to recollect the principles laid down as elements of the whole discussion; for we have still greater need of a correct notion of the whole than we have even of an accurate understanding of the details. We must, therefore, give preference to the former knowledge, and lay up in our memory those principles on which we may rest, in order to arrive at an exact perception of things, and at a certain knowledge of particular objects.
Now one has arrived at that point when one has thoroughly embraced the conceptions, and, if I may so express myself, the most essential forms, and when one has impressed them adequately on one’s senses. For this clear and precise knowledge of the whole, taken together, necessarily facilitates one’s particular perceptions, when one has brought one’s ideas back to the elements and simple terms. In short, a veritable synthesis, comprising the entire circle of the phenomena of the universe, ought to be able to resume in itself, and in a few words, all the particular facts which have been previously studied. This method being useful even to those who are already familiarised with the laws of the universe, I recommend them, while still pursuing without intermission the study of nature, which contributes more than anything else to the tranquillity and happiness of life, to make a concise statement or summary of their opinions.
First of all then, Herodotus, one must determine with exactness the notion comprehended under each separate word, in order to be able to refer to it, as to a certain criterion, the conceptions which emanate from ourselves, the ulterior researches and the difficulties; otherwise the judgment has no foundation. One goes on from demonstration to demonstration ad infinitum; or else one gains nothing beyond mere words. In fact, it is absolutely necessary that in every word we should perceive directly, and without the assistance of any demonstration, the fundamental notion which it expresses, if we wish to have any foundation to which we may refer our researches, our difficulties, and our personal judgments, whatever in other respects may be the criterion which we adopt, whether we take as our standard the impressions produced on our senses, or the actual impression in general; or whether we cling to the idea by itself, or to any other criterion.
We must also note carefully the impressions which we receive in the presence of objects, in order to bring ourselves back to that point in the circumstances in which it is necessary to suspend the judgment, or even when the question is about things, the evidence of which is not immediately perceived.
When these foundations are once laid we may pass to the study of those things, the evidence of which is not immediate. And, first of all, we must admit that nothing can come of that which does not exist; for, were the fact otherwise, then everything would be produced from everything, and there would be no need of any seed. And if that which disappeared were so absolutely destroyed as to become nonexistent, then everything would soon perish, as the things with which they would be dissolved would have no existence. But, in truth, the universal whole always was such as it now is, and always will be such. For there is nothing into which it can change; for there is nothing beyond this universal whole which can penetrate into it, and produce any change in it.
And Epicurus establishes the same principles at the beginning of the great Abridgment; and in the first book of his treatise on Nature.
Now the universal whole is a body; for our senses bear us witness in every case that bodies have a real existence; and the evidence of the senses, as I have said before, ought to be the rule of our reasonings about everything which is not directly perceived. Otherwise, if that which we call the vacuum, or space, or intangible nature, had not a real existence, there would be nothing on which the bodies could be contained, or across which they could move, as we see that they really do move. Let us add to this reflection that one cannot conceive, either in virtue of perception, or of any analogy founded on perception, any general quality peculiar to all beings which is not either an attribute, or an accident of the body, or of the vacuum.
The same principles are laid down in the first, and fourteenth, and fifteenth book of the treatise on Nature; and also in the Great Abridgment.
Now, of bodies, some are combinations, and some the elements out of which these combinations are formed. These last are indivisible, and protected from every kind of transformation; otherwise everything would be resolved into nonexistence. They exist by their own force, in the midst of the dissolution of the combined bodies, being absolutely full, and as such offering no handle for destruction to take hold of. It follows, therefore, as a matter of absolute necessity, that the principles of things must be corporeal, indivisible elements.
The universe is infinite. For that which is finite has an extreme, and that which has an extreme is looked at in relation to something else. Consequently, that which has not an extreme, has no boundary; and if it has no boundary, it must be infinite, and not terminated by any limit. The universe then is infinite, both with reference to the quantity of bodies of which it is made up, and to the magnitude of the vacuum; for if the vacuum were infinite, the bodies being finite, then, the bodies would not be able to rest in any place; they would be transported about, scattered across the infinite vacuum for want of any power to steady themselves, or to keep one another in their places by mutual repulsion. If, on the other hand, the vacuum were finite, the bodies being infinite, then the bodies clearly could never be contained in the vacuum.
Again: the atoms which form the bodies, these full elements from which the combined bodies come and into which they resolve themselves, assume an incalculable variety of forms, for the numerous differences which the bodies present cannot possibly result from an aggregate of the same forms. Each variety of forms contains an infinity of atoms, but there is not for that reason an infinity of atoms; it is only the number of them which is beyond all calculation.
Epicurus adds, a little lower down, that divisibility ad infinitum is impossible; for, says he, the only things which change are the qualities; unless, indeed, one wishes to proceed from division to division, till one arrives absolutely at infinite littleness.
The atoms are in a continual state of motion.
He says, farther on, that they move with an equal rapidity from all eternity, since the vacuum offers no more resistance to the lightest than it does to the heaviest.
Among the atoms, some are separated by great distances, others come very near to one another in the formation of combined bodies, or at times are enveloped by others which are combining; but in this latter case they nevertheless preserve their own peculiar motion, thanks to the nature of the vacuum, which separates the one from the other, and yet offers them no resistance. The solidity which they possess causes them, while knocking against one another, to react the one upon the other, till at last the repeated shocks bring on the dissolution of the combined body; and for all this there is no external cause, the atoms and the vacuum being the only causes.
He says further on that the atoms have no peculiar quality of their own, except from magnitude and weight. As to color, he says in the twelfth book of his Principia that it varies according to the position of the atoms. Moreover, he does not attribute to the atoms any kind of dimensions; and, accordingly, no atom has ever been perceived by the senses; but this expression, if people only recollect what is here said, will by itself offer to the thoughts a sufficient image of the nature of things.
But, again, the worlds also are infinite, whether they resemble this one of ours or whether they are different from it. For as the atoms are, as to their number, infinite, as I have proved above, they necessarily move about at immense distances; for besides, this infinite multitude of atoms of which the world is formed, or by which it is produced, could not be entirely absorbed by one single world, nor even by any worlds the number of which was limited, whether we suppose them like this world of ours or different from it. There is, therefore, no fact inconsistent with an infinity of worlds.
Moreover, there are images resembling, as far as their form goes, the solid bodies which we see, but which differ materially from them in the thinness of their substance. In fact it is not impossible but that there may be in space some secretions of this kind, and an aptitude to form surfaces without depth, and of an extreme thinness; or else that from the solids there may emanate some particles which preserve the connection, the disposition, and the motion which they had in the body. I give the name of images to these representations; and indeed, their movement through the vacuum taking place, without meeting any obstacle or hindrance, perfects all imaginable extent in an inconceivable moment of time; for it is the meeting of obstacles or the absence of obstacles, which produces the rapidity or the slowness of their motion. At all events, a body in motion does not find itself, at any moment imaginable, in two places at the same time; that is quite inconceivable. From whatever point of infinity it arrives at some appreciable moment, and whatever may be the spot in its course in which we perceive its motion, it has evidently quitted that spot at the moment of our thought; for this motion which, as we have admitted up to this point, encounters no obstacle to its rapidity, is wholly in the same condition as that the rapidity of which is diminished by the shock of some resistance.
It is useful also to retain this principle, and to know that the images have an incomparable thinness; which fact indeed is in no respect contradicted by sensible appearances. From which it follows that their rapidity also is incomparable; for they find everywhere an easy passage, and besides, their infinite smallness causes them to experience no shock, or at all events to experience but a very slight one, while an infinite multitude of elements very soon encounter some resistance.
One must not forget that the production of images is simultaneous with the thought; for from the surface of the bodies images of this kind are continually flowing off in an insensible manner indeed, because they are immediately replaced. They preserve for a long time the same disposition, and the same arrangement that the atoms do in the solid body, although, notwithstanding, their form may be sometimes altered. The direct production of images in space is equally instantaneous, because these images are only light substances destitute of depth.
But there are other manners in which natures of this kind are produced; for there is nothing in all this which at all contradicts the senses, if one only considers in what way the senses are exercised, and if one is inclined to explain the relation which is established between external objects and ourselves. Also, one must admit that something passes from external objects into us in order to produce in us sight and the knowledge of forms; for it is difficult to conceive that external objects can affect us through the medium of the air which is between us and them, or by means of rays, whatever emissions proceed from us to them, so as to give us an impression of their form and color. This phenomenon, on the contrary, is perfectly explained if we admit that certain images of the same color, of the same shape, and of a proportionate magnitude pass from these objects to us, and so arrive at being seen and comprehended. These images are animated by an exceeding rapidity, and, as on the other side, the solid object forming a compact mass, and comprising a vast quantity of atoms, emits always the same quantity of particles, the vision is continued, and only produces in us one single perception which preserves always the same relation to the object. Every conception, every sensible perception which bears upon the form or the other attributes of these images, is only the same form of the solid perceived directly, either in virtue of a sort of actual and continued condensation of the image, or in consequence of the traces which it has left in us.
Error and false judgments always depend upon the supposition that a preconceived idea will be confirmed, or at all events will not be overturned, by evidence. Then, when it is not confirmed, we form our judgment in virtue of a sort of initiation of the thoughts connected, it is true with the perception, and with a direct representation; but still connected also with a conception peculiar to ourselves, which is the parent of error. In fact the representations which intelligence reflects like a mirror, whether one perceives them in a dream, or by any other conceptions of the intellect, or of any other of the criteria, can never resemble the objects that one calls real and true, unless there were objects of this kind perceived directly. And, on the other side, error could not be possible if we did not receive some other motion also, a sort of initiative of intelligence connected; it is true with direct representation, but going beyond that representative. These conceptions being connected with the direct perception which produces the representation, but going beyond it, in consequence of a motion peculiar to the individual thought, produces error when it is not confirmed by evidence, or when it is contradicted by evidence; but when it is confirmed, or when it is not contradicted by evidence, then it produces truth.
We must carefully preserve these principles in order not to reject the authority of the faculties which perceive truth directly; and not, on the other hand, to allow what is false to be established with equal firmness, so as to throw everything into confusion.