"I once kept a viper in a sealed glass jar until it died, to observe the effects of air deprivation."

"The business of a philosopher is to give an account of things as they are."

"I have observed that mercury, when heated, will rise in a tube against its natural tendency."

"I am not ashamed to confess that I have learned more from observation than from all the books I have ever read."

"I have always looked upon the study of nature as a delightful and profitable employment."