"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things."
- René Descartes (1596-1650)
"I am convinced that the unwritten knowledge scattered among men of different callings surpasses in quantity and in importance anything we find in books, and that the greater part of our wealth has yet to be recorded."
- Gottfried Leibniz (1646-1716)
"Reading furnishes the mind only with materials of knowledge; it is thinking that makes what we read ours."
- John Locke (1632–1704)
"Generally speaking, the errors in religion are dangerous; those in philosophy only ridiculous."
- David Hume (1711-1776)
"The death of dogma is the birth of morality."
- Immanuel Kant (1724 – 1804)
"Religious wars are not caused by the fact that there is more than one religion, but by the spirit of intolerance...the spread of which can only be regarded as the total eclipse of human reason. "
Baron de Montesquieu (1689 – 1755)
"Humanity may endure the loss of everything: all its possessions may be torn away without infringing its true dignity; — all but the possibility of improvement."
- Johann Gottlieb Fichte (1762-1814)
"The bad thing about all religions is that, instead of being able to confess their allegorical nature, they have to conceal it; accordingly, they parade their doctrines in all seriousness as true sensu proprio, and as absurdities form an essential part of these doctrines we have the great mischief of a continual fraud. Nay, what is worse, the day arrives when they are no longer true sensu proprio, and then there is an end of them; so that, in that respect, it would be better to admit their allegorical nature at once. But the difficulty is to teach the multitude that something can be both true and untrue at the same time. Since all religions are in a greater or less degree of this nature, we must recognise the fact that mankind cannot get on without a certain amount of absurdity, that absurdity is an element in its existence, and illusion indispensable; as indeed other aspects of life testify."
- Arthur Schopenhauer (1788 – 1860)