Canonical Reference: Dhp 82 Verified Source

“Even as a deep, still lake is clear and unruffled, so the wise become thoroughly serene upon hearing the teachings of Dhamma.”

Canonical Pali Original: Yathāpi rahado gambhīro, vippasanno anāvilo; Evaṃ dhammāni sutvāna, vippasīdanti paṇḍitā.

— Gautam Buddha
The Awakened One, Founder of Dhamma
Historical Setting & Context:

Pali Canon: Dhammapada 6.82 on the calming, clarifying effect of wisdom and ethical contemplation.