These are times in which a genius would wish to live. It is not in the still calm of life, or in the repose of a pacific station, that great characters are formed. The habits of a vigorous mind are formed in contending with difficulties. Great necessities call out great virtues.

Abigail Adams (1744-1818) American correspondent, First Lady (1797-1801)

Letter to John Quincy Adams (19 Jan 1780)

Probable source of the similar "Great necessities call forth great leaders," usually cited (but not found) as a letter to Thomas Jefferson.