saI ni kweI nan [or] sI neI kwa non
(Latin) something necessary; indispensable item or condition.
This Latin expression means, literally, “without which, not.” In other words, without the “sine qua non,” the thing in question can not exist.
“Conflict is the gadfly of thought. It stirs us to observation and memory. It instigates invention. It shocks us out of sheep-like passivity, and sets us at noting and contriving…conflict is a sine qua non of reflection and ingenuity.” John Dewey
Chastity is the sine qua non of lucidity and concentration.” Dietrich Bonhoeffer