“I knew that when the great guiding spirit cleaves humanity into two antagonistic halves, I will be with the people.”

Nichts halb zu thun ist edler Geister Art.
Oberon, Song 5, st. 30 http://www.archive.org/stream/oberon02187gut/7ober10.txt; translation from A. B. Faust (ed.) Oberon (New York: F. S. Crofts, 1940) p. 326.

Source: Pale Fire

Variant (perhaps a paraphrase of this passage): It is not reason which is the guide of life, but custom.
An Enquiry Concerning Human Understanding (1748)
Context: Custom, then, is the great guide of human life. It is that principle alone which renders our experience useful to us, and makes us expect, for the future, a similar train of events with those which have appeared in the past. Without the influence of custom, we should be entirely ignorant of every matter of fact beyond what is immediately present to the memory and senses. We should never know how to adjust means to ends, or to employ our natural powers in the production of any effect. There would be an end at once of all action, as well as of the chief part of speculation.

Response in 1965, to Moshe Bejski, one of the Schindlerjuden, who later a became a justice on the Supreme Court of Israel and president of the Commission to honor the Righteous Among the Nations, as quoted in "Schindler : Why did he do it?" (2010) by Louis Bülow http://www.auschwitz.dk/why/why.htm.

Interview with BBC Radio 1FM (1994)

Quote in a letter to his friend J. B. Pierret, 18 September 1818, from the Forest of Boixe; as quoted in Eugene Delacroix – selected letters 1813 – 1863”, ed. and translation Jean Stewart, art Works MFA publications, Museum of Fine Art Boston, 2001, p. 41
1815 - 1830

As quoted in, All 3 Major Israeli TV Channels Declare Netanyahu Victor In Election, April 9 2019, The Daily Wire
2010s, 2019

Source: Northanger Abbey