“Can intellect aid understanding? It helps in the beginning but cannot give full enlightenment. The mind is the main instrument to gain enlightenment, but enlightenment is only reached when the mind stops.”

Source: A Letter Addressed to the Abbe Raynal on the Affairs of North America

Fearless Death: Buddhist Wisdom on the Art of Dying (2012)

The Lessons of History (1968)‎, p. 72 (co-authored with Ariel Durant)

Les Loix du Mouvement et du Repos, déduites d'un Principe Métaphysique (1746)

Writing for the court, Milk Wagon Drivers Union of Chicago, Local 753. v. Meadowmoor Dairies, Inc., 312 U.S. 287 (1941).
Judicial opinions
Context: It must never be forgotten, however, that the Bill of Rights was the child of the Enlightenment. Back of the guarantee of free speech lay faith in the power of an appeal to reason by all the peaceful means for gaining access to the mind. It was in order to avert force and explosions due to restrictions upon rational modes of communication that the guarantee of free speech was given a generous scope. But utterance in a context of violence can lose its significance as an appeal to reason and become part of an instrument of force. Such utterance was not meant to be sheltered by the Constitution.

Letter to Éleuthère Irénée du Pont de Nemours (24 April 1816)
1810s

And the Weak Suffer What They Must? : Europe's Crisis and America's Economic Future (2016), Ch. 4, Trojan Horse