Skepticism and faith are no less necessary. Skepticism, riddling the faith of yesterday, prepared the way for the faith of tomorrow.

Doubt is not below knowledge, but above it.

There is one thing a professor can be absolutely certain of: almost every student entering the university believes, or says he believes, that truth is relative.

Doubt is the vestibule which all must pass, before they can enter into the temple of truth.

What has not been examined impartially has not been well examined. Skepticism is therefore the first step toward truth.

Doubt is an element of criticism, and the tendency of criticism is necessarily skeptical.

Man's most valuable trait is a judicious sense of what not to believe.

A wise skepticism is the first attribute of a good critic.

Let the greatest part of the news thou hearest be the least part of what thou believest, lest the greater part of what thou believest be the least part of what is true.

When all beliefs are challenged together, the just and necessary ones have a chance to step forward and to re-establish themselves alone.