That fear first created the gods is perhaps as true as anything so brief could be on so great a subject.

Imagination is potentially infinite. Though actually we are limited to the types of experience for which we possess organs, those organs are somewhat plastic. Opportunity will change their scope and even their center.

Saints cannot arise where there have been no warriors, nor philosophers where a prying beast does not remain hidden in the depths.

Eternal vigilance is the price of knowledge.

At best, the true philosopher can fulfil his mission very imperfectly, which is to pilot himself, or at most a few voluntary companions who may find themselves in the same boat.

Progress, far from consisting in change, depends on retentiveness. Those who cannot remember the past are condemned to repeat it.

...science is nothing but developed perception, interpreted intent, common-sense rounded out and minutely articulated. It is therefore as much an instinctive product, as much a stepping forth of human courage in the dark, as is any inevitable dream or impulsive action.