The Yaksha asked,—‘What, O king is said to be knowledge? What, tranquillity? What constitutes mercy? And what hath been called simplicity?’ Yudhishthira answered,—‘True knowledge is that of Divinity. True tranquillity is that of the heart. Mercy consists in wishing happiness to all. And simplicity is equanimity of heart.’

In plain words: The Yaksha, a nature spirit testing King Yudhishthira, asks about knowledge, peace, mercy and simplicity. Yudhishthira says real knowledge is knowing God, real peace is a calm heart, mercy is wanting everyone to be happy, and simplicity is keeping an even, steady heart.