The Chinese word for endurance
In What My Bones Know, Stephanie Foo says:
It made perfect sense to me later in life when I discovered that the Chinese word for endurance is simply the word knife on top of the word heart. You walk around with a knife in your heart. You do it with stoicism. This is the apex of being.
The character is 忍 (rěn), a compound ideograph written with the 心 (xīn) radical “heart” under the character 刃 (rèn) “knife edge.” The experience of enduring hardship or pain is indeed visually rendered with a knife’s edge above the heart.