This more general solution, as Peirce was careful to state, does not detract from the honor due either to Leverrier or to Adams. Their masterly calculations, the difficulty of which no one who has not had some experience of the subject can appreciate, remain as an imperishable monument to both, as does also Peirce’s to him. CHAPTER V FORMATION OF PLANETS In our first two chapters we saw what sign-posts in the sky there are pointing to the course evolution of a solar system probably follows, and secondly, what evidence there is that our system took this road. We now come to a question not so easy to precise,—the actual details of the journey. It is always difficult to descend from a glittering panoramic survey to particular path-finding. The obstacles loom so much larger on a near approach. Most men shy at decisions and shun self-committal to any positive course, but when it comes to constructing a cosmogony, few at all qualified hesitate to frame one if the old does not suit. The safety in so doing lies in the fact that nothing in particular happens if it refuses to work. Its absurdity is promptly shown up, it is true, by some one else. For there is almost as good a trade in exposing cosmogonies as in constructing them. But no special opprobrium attaches to failure, because everybody has failed, from Laplace down, or up, as you are pleased to consider it. Besides it is really not so easy to do, as one is tempted to believe before his book is published. Then only does the difficulty dawn, with a speed and clarity inversely proportional to the previous relation of the critic to the author. For the author himself is apt to be blind. With the fatal fondness of a parent for his offspring it is rare for the defects to be so glaringly apparent to their perpetrator. At the worst he considers them venial faults which can be glossed away. Attacking the subject in this judicial spirit, the reader can hardly expect me to satisfy him with a cosmogony entirely home-made, but at best to pursue a happy middle course between creator and critic, advocating only such portions as happen to be my own, while sternly exposing the mistakes of others. In undertaking the hazardous climb toward the origin of things two qualities are necessary in the explorer: a quick eye for possibilities and a steady head in testing them. Without the discernment to perceive relations no ascent to first principles is possible; and without the support of quantitative criterion, one is in danger of becoming giddy from one’s own imagination. Congruities must first hint at a path; physical laws then determine its feasibility.