“You never know how much you really believe anything until its truth or falsehood becomes a matter of life and death to you.”
A Grief Observed (1961)
Context: You never know how much you really believe anything until its truth or falsehood becomes a matter of life and death to you. It is easy to you believe a rope to be strong and sound as long as you are merely using it to cord a box. But suppose that you had to hang by that rope over a precipice. Wouldn't you then first discover how much you really trusted it? … Only a real risk tests the reality of a belief.
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Clive Staples Lewis 272
Christian apologist, novelist, and Medievalist 1898–1963Related quotes

“People don't care how much you know until they know how much you care”
Variant: No one cares how much you know, until they know how much you care

Kōnosuke Matsushita in: Cherry blossoms and robotics, 1983; Cited in: John R. Schermerhorn (1993), Management for productivity, p. 170

“How can you do anything until you have seen everything, or as much as you can?”
Source: The Light That Failed

Variant: Don't celebrate yet, Ms. Lane. Don't believe anything is dead until you've burned it, poked around in its ashes, and then waited a day or two to see if anything rises from them.
Source: Bloodfever

Source: Aleph (2011)
Context: Routine has nothing to do with repetition. To become really good at anything, you have to practice and repeat, practice and repeat, until the technique becomes intuitive.

"4th Foundational Falsehood of Creationism" https://www.youtube.com/watch?v=80nhqGfN6t8, Youtube (December 25, 2007)
Youtube, Foundational Falsehoods of Creationism
“No matter how much you hate or how much you suffer, you can't bring the dead back to life”