"Sordet cognita veritas" is a shrewd aphorism of Seneca. A truth,…

The one condition under which all powers, and consequently the intellectual faculties, are developed, is exercise.

The question—Is Truth, or is the Mental Exercise in the pursuit of truth, the superior end?—this is perhaps the most curious theoretical, and certainly the most important practical, problem in the whole compass of philosophy.

The primary principle of education is the determination of the pupil to self-activity — the doing nothing for him which he is able to do for himself.

Truth like a torch, the more 'tis shook, it shines.

Be sober, and to doubt prepense, These are the sinews of good sense.

[T]he sciences always studied with keenest interest are those in a state of progress and uncertainty: absolute certainty and absolute completion would be the paralysis of any study; and the last worst calamity that could befall man... …