"If a single cell, under appropriate conditions, becomes a man in the space of a few years, there can surely be no difficulty in understanding how, under appropriate conditions, a cell may, in the course of untold millions of years, give origin to the human race."

"Evolution is an integration of matter and concomitant dissipation of motion during which the matter passes from an indefinite incoherent homogeneity to a definite coherent heterogeneity, and during which the retained motion undergoes a parallel transformation."

"This survival of the fittest implies multiplication of the fittest.{The phrase 'survival of the fittest' was not originated by Charles Darwin, though he discussed Spencer's 'excellent expression' in a letter to Alfred Russel Wallace (Jul 1866).}"

"This survival of the fittest which I have here sought to express in mechanical terms, is that which Mr. Darwin has called 'natural selection, or the preservation of favoured races in the struggle for life."

"Those who have never entered upon scientific pursuits know not a tithe of the poetry by which they are surrounded."

"Only when Genius is married to Science can the highest results be produced."

"Science is organized knowledge."