According to Aristotle, none of the products of Nature are due to chance. His proof is this: That which is due to chance does not reappear constantly nor frequently, but all products of Nature reappear either constantly or at least frequently. The heavens, with all that they contain, are constant; they never change, as has been explained, neither as regards their essence nor as regards their place. But in the sublunary world we find both things which are constant and things which reappear frequently [though not constantly]. Thus, e.g., the heat of fire and the downward tendency of a stone are constant properties, whilst the form and life of the individuals in each species are the same in most cases. All this is clear. If the parts of the Universe are not accidental, how can the whole Universe be considered as the result of chance? Therefore the existence of the Universe is not due to chance. The following is, in short, the objection which Aristotle raises against one of the earlier philosophers who assumed that the Universe is the result of chance, and that it came into existence by itself, without any cause. Some assume that the heavens and the whole Universe came into existence spontaneously, as well as the rotation and motion [of the spheres], which has produced the variety of things and established their present order. This opinion implies a great absurdity. They admit that animals and plants do not owe their existence or production to chance, but to a certain cause, be that cause Nature, or reason, or the like; e.g., they do not assume that everything might be formed by chance of a certain seed or semen, but that of a certain seed only an olive-tree is produced, and of a certain semen only a human being is developed. And yet they think that the heavens, and those bodies which appear divine among the rest of bodies, came into existence spontaneously, without the action of any such cause as produces plants and animals. Having thus examined this theory, Aristotle then proceeds to refute it at greater length. It is therefore clear that Aristotle believes and proves that things in real existence are not accidental; they cannot be accidental, because they are essential, i.e., there is a cause which necessitates that they should be in their actual condition, and on account of that cause they are just as they in reality are. This has been proved, and it is the opinion of Aristotle. But I do not think that, according to Aristotle, the rejection of the spontaneous origin of things implies the admission of Design and Will. For as it is impossible to reconcile two opposites, so it is impossible to reconcile the two theories, that of necessary existence by causality, and that of Creation by the desire and will of a Creator. For the necessary existence assumed by Aristotle must be understood in this sense, that for everything that is not the product of work there must be a certain cause that produces it with its