Fundamental progress has to do with the reinterpretation of basic ideas.

What we perceive as the present is the vivid fringe of memory tinged with anticipation.

In the study of ideas, it is necessary to remember that insistence on hard-headed clarity issues from sentimental feeling, as it were a mist, cloaking the perplexities of fact. Insistence on clarity at all costs is based on sheer superstition as to the mode in which human intelligence functions. Our reasonings grasp at straws for premises and float on gossamers for deductions.

It is the business of the future to be dangerous.

In a sense, knowledge shrinks as wisdom grows, for details are swallowed up in principles. The details for knowledge which are important, will be picked up ad hoc in each avocation of life, but the habit of the active utilization of well-understood principles is the final possession of WISDOM.

The deepest definition of youth is life as yet untouched by tragedy.

After you understand about the sun and the stars and the rotation of the earth, you may still miss the radiance of the sunset.