ethics, morality, virtue
悳 centers on moral character: ethics, virtue, and right conduct. The given meanings all point to an inner quality of goodness and principled behavior.
悳 is a variant form of 徳, combining 直 (straight, direct) with 心 (heart/mind) to express an upright inner character. The exact historical relationship between 悳 and 徳 is uncertain, but both convey the idea of moral virtue.
A straight (直) heart (心) is the foundation of ethics and virtue. Picture a person whose inner compass is perfectly aligned, making every choice morally upright.
For トク, imagine a person of virtue speaking about ethics: their talk (トーク, to-ku) is always principled. Talk -> トク, and the straight heart guides every word.
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