The geologists were a hardy class, not likely to be much hurt by Adams's learning, nor did he throw away much concern on their account. He undertook the task chiefly to educate, not them, but himself, and if Sir Isaac Newton had, like Sir Charles Lyell, asked him to explain for Americans his last edition of the "Principia," Adams would have jumped at the chance. Unfortunately the mere reading such works for amusement is quite a different matter from studying them for criticism. Ignorance must always begin at the beginning. Adams must inevitably have begun by asking Sir Isaac for an intelligible reason why the apple fell to the ground. He did not know enough to be satisfied with the fact. The Law of Gravitation was so-and-so, but what was Gravitation? and he would have been thrown quite off his base if Sir Isaac had answered that he did not know. At the very outset Adams struck on Sir Charles's Glacial Theory or theories. He was ignorant enough to think that the glacial epoch looked like a chasm between him and a uniformitarian world. If the glacial period were uniformity, what was catastrophe? To him the two or three labored guesses that Sir Charles suggested or borrowed to explain glaciation were proof of nothing, and were quite unsolid as support for so immense a superstructure as geological uniformity. If one were at liberty to be as lax in science as in theology, and to assume unity from the start, one might better say so, as the Church did, and not invite attack by appearing weak in evidence. Naturally a young man, altogether ignorant, could not say this to Sir Charles Lyell or Sir Isaac Newton; but he was forced to state Sir Charles's views, which he thought weak as hypotheses and worthless as proofs. Sir Charles himself seemed shy of them. Adams hinted his heresies in vain. At last he resorted to what he thought the bold experiment of inserting a sentence in the text, intended to provoke correction. "The introduction [by Louis Agassiz] of this new geological agent seemed at first sight inconsistent with Sir Charles's argument, obliging him to allow that causes had in fact existed on the earth capable of producing more violent geological changes than would be possible in our own day." The hint produced no effect. Sir Charles said not a word; he let the paragraph stand; and Adams never knew whether the great Uniformitarian was strict or lax in his uniformitarian creed; but he doubted.