I am too much of a skeptic to deny the possibility of anything.

From the dawn of exact knowledge to the present day, observation, experiment, and speculation have gone hand in hand; and, whenever science has halted or strayed from the right path, it has been, either because its votaries have been content with mere unverified or unverifiable speculation (and this is the commonest case, because observation and experiment are hard work, while speculation is amusing); or it has been, because the accumulation of details of observation has for a time excluded speculation.

The cradle of every science is surrounded by dead theologians as that of Hercules was with strangled serpents

If a little knowledge is dangerous, where is a man who has so much as to be out of danger?

Ecclesiasticism in science is only unfaithfulness to truth

Science is nothing but trained and organized common sense, differing from the latter only as a veteran may differ from a raw recruit: and its methods differ from those of common sense only as far as the guardsman's cut and thrust differ from the manner in which a savage wields his club.