“I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am convinced that natural selection has been the most important, but not the exclusive, means of modification.”

“I think it inevitably follows, that as new species in the course of time are formed through natural selection, others will become rarer and rarer, and finally extinct. The forms which stand in closest competition with those undergoing modification and improvement will naturally suffer most.”

“The idea that one can go to the fossil record and expect to empirically recover an ancestor-descendant sequence, be it of species, genera, families, or whatever, has been, and continues to be, a pernicious illusion.”

“One species on the planet, and one species only, has reached the point of being able to have an impact on the evolutionary fortunes of all other species and upon the functioning of all ecosystems. We also have, in a way that is not true for any other species, a relationship to the planet as a whole and to the future. We live with all life.”

“I am a rare species, not a stereotype.”

“The selective voluntary blindness of human beings allows them to ignore the moral consequences of their choices. It has been one of the species' most valuable traits, in terms of the survival of any particular human community.”