On my return from the first exploration of the canyons of the Colorado — John Wesley Powell

"Scientific education is catholic; it embraces the whole field of human learning. No student can master all knowledge in the short years of his academic life, but a young man of ability and industry may reasonably hope to master the outlines of science, obtain a deep insight into the methods of scientific research, and at the same time secure an initiation into some one of the departments of science, in such a manner that he may fully appreciate the multitude of facts upon which scientific conclusions rest, and be prepared to enter the field of scientific research himself and make additions to the sum of human knowledge."

"In science nothing can be permanently accepted but that which is true, and whatever is accepted as true is challenged again and again. It is an axiom in science that no truth can be so sacred that it may not be questioned. When that which has been accepted as true has the least doubt thrown upon it, scientific men at once re-examine the subject. No opinion is sacred. “It ought to be” is never heard in scientific circles. "It seems to be" and "we think it is" is the modest language of scientific literature."

"Scientific education is a training in mental integrity. All along the history of culture from savagery to modern civilization men have imagined what ought to be, and then have tried to prove it true. This is the very spirit of metaphysic philosophy. When the imagination is not disciplined by unrelenting facts, it invents falsehood, and, when error has thus been invented, the heavens and the earth are ransacked for its proof."

"We have an unknown distance yet to run, an unknown river to explore. What falls there are, we know not; what rocks beset the channel, we know not; what walls rise over the river, we know not. Ah, well! we may conjecture many things. The men talk as cheerfully as ever; jests are bandied about freely this morning; but to me the cheer is somber and the jests are ghastly."

"The verb is relatively of much greater importance in an Indian tongue than in a civilized language."

"The landscape everywhere, away from the river, is of rock—cliffs of rock, tables of rock, plateaus of rock, terraces of rock, crags of rock—ten thousand strangely carved forms; rocks everywhere, and no vegetation, no soil, no sand. In long, gentle curves the river winds about these rocks."