The more experiences and experiments accumulate in the exploration of nature, the more precarious the theories become. But it is not always good to discard them immediately on this account. For every hypothesis which once was sound was useful for thinking of previous phenomena in the proper interrelations and for keeping them in context. We ought to set down contradictory experiences separately, until enough have accumulated to make building a new structure worthwhile.

Man is always partial and is quite right to be. Even impartiality is partial.

Libraries can in general be too narrow or too wide for the soul.

To receive applause for works which do not demand all our powers hinders our advance towards a perfecting of our spirit. It usually means that thereafter we stand still.

Everyone is perfectly willing to learn from unpleasant experience - if only the damage of the first lesson could be repaired.

Deliberate virtue is never worth much: The virtue of feeling or habit is the thing.

With a pen in my hand I have successfully stormed bulwarks from which others armed with sword and excommunication have been repulsed.