If it be true that all Governments rest on opinion, it is no less true, that the strength of opinion in each individual, and its practical influence on his conduct, depend much on the number which he supposes to have entertained the same opinion. The reason of man, like man himself, is timid and cautious when left alone; and acquires firmness and confidence, in proportion to the number with which it is associated.
Notes from Wikiquote
Partially quoted in by Michael Kruse (September/October 2018): The Weekend at Yale That Changed American Politics. In: Politico.com. Archived from the original on February 2, 2019. The last quoted sentence means according to Associate Justice of the U.S. Supreme Court Antonin Scalia in the aforementioned source this: Intellectual courage is based on strength in numbers.