I have long discovered that geologists never read each other's works, and that the only object in writing a book is a proof of earnestness.

History shows that the human mind, fed by constant accessions of knowledge, periodically grows too large for its theoretical coverings, and bursts them asunder to appear in new habiliments, as the feeding and growing grub, at intervals, casts its too narrow skin and assumes another.

Although I am fully convinced of the truth of the views given in this volume under the form of an abstract, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine... I look with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality.

A celebrated author and divine has written to me that he has gradually learned to see that it is just as noble a conception of the Deity to believe that he created a few original forms capable of self-development into other and needful forms, as to believe that he required a fresh act of creation to supply the voids caused by the action of his laws.

The limit of man s knowledge in any subject possesses a high interest which is perhaps increased by its close neighbourhood to the realms of imagination.

The moral faculties are generally esteemed, and with justice, as of higher value than the intellectual powers. But we should always bear in mind that the activity of the mind in vividly recalling past impressions is one of the fundamental though secondary bases of conscience. This fact affords the strongest argument for educating and stimulating in all possible ways the intellectual faculties of every human being.

The formation of different languages and of distinct species and the proofs that both have been developed through a gradual process, are curiously parallel.