"The earth is a paradise, but men make it a hell."

"The natural system will always remain the greatest goal for botanists."

"Nature has always been my school, and my teachers have been the trees, the flowers, and the stones."

"Homo Sapiens. Diurnus; varians cultura, loco. Europaeus albus, Asiaticus luridus, Africanus niger, Americanus rufus."

"I have done more for the advancement of natural history than anyone else."