"A man who dares to waste one hour of time has not discovered the value of life."

"The greatest discovery of all is that the world is not as we thought it was."

"The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an agnostic."

"The expression of the emotions in man and animals is a study of the utmost interest."

"The love of experiment and the patient observation of nature are the two great qualifications for a naturalist."