| Quotation | Thinker | Nationality |
| 'And when you gaze long into an abyss the abyss also gazes into you' | |
| '...my country is the world and my religion is to do good' | |
| 'People will not look forward to posterity, who never look backward to their ancestors' | |
| 'If God did not exist, it would be necessary to invent him' | |
| 'Man...hath by nature a power...to preserve his property - that is, his life, liberty, and estate' | |
| 'Faith is a living, bold trust in God's grace' | |
| 'History is nothing but the actions of men in pursuit of their ends' | |
| 'The struggle itself toward the heights is enough to fill a man's heart. One must imagine Sisyphus happy' | |
| 'It is far safer to be feared than loved if you cannot be both' | |
| 'Till women are more rationally educated, the progress in human virtue and improvement in knowledge must receive continual checks' | |
| | Quotation | Thinker | Nationality |
| 'No pleasure is comparable to the standing upon the vantage-ground of truth' | |
| 'Whatever can be proved to be good, must be so by being shown to be a means to something admitted to be good without proof' | |
| 'In the long run we are all dead' | |
| 'I do not feel obliged to believe that the same God who has endowed us with senses, reason, and intellect has intended us to forgo their use' | |
| '...the life of man, solitary, poor, nasty, brutish, and short' | |
| 'I feel most deeply that this whole question of creation is too profound for human intellect' | |
| 'I think, therefore I am' | |
| 'The ego is not master in its own house' | |
| 'Man is born free; and everywhere he is in chains' | |
| 'A man must always live by his work, and his wages must at least be sufficient to maintain him' | |
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