"The more specific idea of Evolution now reached is - a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, accompanying the dissipation of motion and integration of matter."

"There is no origin for the idea of an afterlife, save the conclusion which the savage draws from the notion suggested by dreams."

"The idea of disembodied spirits is wholly unsupported by evidence, and I cannot accept it."

"How often misused words generate misleading thoughts."

"No phrase can convey the idea of surprise so vividly as opening the eyes and raising the eyebrows. A shrug of the shoulders would lose much by translation into words."