The true nature of things is in their particulars, not in generalities; we know the world through its infinite variations, not through abstract rules that pretend to govern them.

The mind of man has perforce been made analogous to a mirror, or to a vessel, which can be filled with the images or ideas of things external. But this is a most inadequate and false representation of what takes place in the mind when it is occupied with the pursuit of truth.

The facts of observation stand like an iron wall against which the most ardent desire for belief dashes itself in vain.

The great tragedy of science—the slaying of a beautiful hypothesis by an ugly fact.