Danske citater:

• At øve godhed ud over menneskehedens skranker, d.v.s. menneskelighed mod dyr, synes at være en af de senest erhvervede sædelige dyder.
• Dyrene føler, som mennesket, glæde smerte, lykke og ulykke. De rammes af de samme sindsbevægelser.
• Et menneske, som tør spilde en time af sit liv, har ikke opdaget livets værdi.
• It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change.

Engelske citater:

• A man who dares to waste one hour of time has not discovered the value of life.
• As for future life, every person must judge for themself between conflicting vague possibilities.
• I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection.
• I love fools' experiments. I am always making them.
• It has been a bitter moritification for me to digest the conclusion that the 'race is for the strong' and that I shall probably do little. more but be content to admire the strides others made in science.
• Man is descended from a hairy, tailed quadruped, probably arboreal in its habits.
• The highest possible stage in moral culture is when we recognise that we ought to control our thoughts.
• The universe we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil, no good, nothing but blind, pitiless indifference.