When I am sometimes struck by certain truths, dressed in all the brilliance which pure virtues possess, but feeling unable to form a rational whole of these virtues when they are not arranged in an orderly manner, I should often have yielded to discouragement, if I had not read in Bossuet’s _Traité du libre arbitre_ these words: “When we begin to reason, we must first consider this as indubitable, that we may know _with complete certainty_ many things of which we do not understand their corollaries, nor all their results. The first rule of our logic is that we must not abandon truths which we have once known, whatever difficulties may present themselves when we are trying to deal with them; but that we must hold both ends of the chain firmly, although we may not be able to see the middle by which the two ends are linked.” THE IDEAS OF PLATO A philosopher said to me: “Since we can know nothing of the beyond, let us make a virtue of necessity, and learn exactly what there is on our side of the veil.” The advice is excellent. Astronomy teaches us that perfect order reigns in the sphere studied by that science. The world may be the result of certain chemical combinations which have met by chance; but if chance has introduced order in these chemical combinations, it might as easily derange them and replace them by disorder; yet the astronomers have not succeeded in discovering the least indication of disorder in their domain; that we know positively. It is generally admitted that the world has had a beginning; is it reason or the absence of reason that we should expect to find at the origin of the world? Does it proceed so regularly in obedience to laws? Sages have said, “Laws govern matter, forces, movements, all things that _are_, but might not have been, just as the world is or exists, but might not have been.” Since Darwin wrote, much discussion has taken place with regard to the origin of species, no one has thought of asking whether the Greek philosophers had anything to say on the subject. If, for instance, it had been discovered that the law of certain sidereal phenomena compelled a circular or elliptical movement, or any other geometrical form, then this law, in itself, would be a geometrical idea; that could exist, although the phenomenon in which it was realised, might disappear with the world itself.