“I have always loved to begin with the facts, to observe them, to walk in the light of experiment and demonstrate as much as possible, and to discuss the results.”

“From whatever I have been able to observe up to this time the series of strata which form the visible crust of the earth appear to me classified in four general and successive orders. These four orders can be conceived to be four very large strata, as they really are, so that wherever they are exposed, they are disposed one above the other, always in the same order.”

“[Fossils found in the Secondary formation are] unrefined and imperfect [species and the species in the Tertiary formation] are very perfect and wholly similar to those that are seen in the modern sea. [Thus] as many ages have elapsed during the elevation of the Alps, as there are races of organic fossil bodies embedded within the strata.”

“With the sole guidance of our practical knowledge of those physical agents which we see actually used in the continuous workings of nature, and of our knowledge of the respective effects induced by the same workings, we can with reasonable basis surmise what the forces were which acted even in the remotest times.”