Date: 1664

"The parts of the blood which penetrate as far as the brain serve not only to nourish and sustain its substance, but also and primarily to produce in it a certain very fine wind, or rather a very lively and pure flame, which is called the animal spirits."

— Descartes, René (1596-1650)

Date: 1665

"Absence lessens moderate passions and intensifies great ones, as the wind blows out a candle but fans up a fire"

— La Rochefoucauld, François, duc de (1613-1680)

Date: w. 1628, published in 1684, 1701

"For the human mind has within it a sort of spark of the divine, in which the first seeds of useful ways of thinking are sown, seeds which, however neglected and stifled by studies which impede them, often bear fruit of their own accord."

— Descartes, René (1596-1650)

Date: 1721, 1722

"Nature, industriously favourable to men, hath not bounded itself in giving desires to men, she was willing that we should have them too, and that we should be the animated instruments of their felicity: she hath put in us the flame of the passions, to make them live easy."

— Charles-Louis de Secondat, Baron de La Brède et de Montesquieu (1689-1755)

Date: 1721, 1722

"I think myself almost annihilated; and I do not become sensible of my existence, till a dismal jealousy comes to kindle and produce in my heart, fear, suspicions, hatred and regret."

— Charles-Louis de Secondat, Baron de La Brède et de Montesquieu (1689-1755)

Date: 1748, 1749

"Without proper food the soul languishes, raves, and dies with faintness. It is like a taper, which revives in the moment it is going to be extinguished."

— Julien Offray de La Mettrie (1709-1751)