To Thales the primary question was not what do we know, but how do we know it.

Personal beauty is a greater recommendation than any letter of introduction

It is not sufficient to know what one ought to say, but one must also know how to say it

There are things which seem incredible to most men who have not studied mathematics.

To the sober person adventurous conduct often seems insanity.

One must learn by doing the thing, for though you think you know it, you have no certainty until you try