Immanuel Kant

“Enlightenment is man's release from his self-incurred tutelage. Tutelage is man's inability to make use of his understanding without direction from another. Self-incurred is this tutelage when its cause lies not in lack of reason but in lack of resolution and courage to use it without direction from another. Sapere aude! 'Have courage to use your own reason!'- that is the motto of enlightenment.”

“Two things fill the mind with ever new and increasing admiration and awe, the more often and steadily we reflect upon them: the starry heavens above me and the moral law within me. I do not seek or conjecture either of them as if they were veiled obscurities or extravagances beyond the horizon of my vision; I see them before me and connect them immediately with the consciousness of my existence.”

“Rules for happiness: something to do, someone to love, something to hope for.”

“Settle, for sure and universally, what conduct will promote the happiness of a rational being.”

“The death of dogma is the birth of morality.”

“In every department of physical science there is only so much science, properly so-called, as there is mathematics.”