The courage to speak truth without hesitation.

Wei Zheng (580–643), the eminent minister of the era of Emperor Taizong of Tang (598–649), is the most famous remonstrating official in Chinese history. According to the Biography of Wei Zheng in the Old Book of Tang, he submitted more than two hundred remonstrances during the reign. His remonstrance was the very model of "直言不諱" — speaking the straight truth without flinching. When Taizong pushed for large construction works, Wei Zheng blocked him: "The people are exhausted." When the emperor sought to enlarge his harem, he admonished him directly: "Frugality is the foundation of the state." Taizong sometimes flew into a rage, crying, "I must kill this country bumpkin," but when Empress Zhangsun soothed him, saying, "That there is a minister who remonstrates is proof of an enlightened ruler," he would again accept Wei Zheng's words. When Wei Zheng died, Taizong left the famous saying: "With bronze as a mirror, one can straighten one's cap and robes; with history as a mirror, one can know the rise and fall of states; with a man as a mirror, one can discern gain and loss. Wei Zheng is gone, and I have lost a mirror." Thus "speaking straight without flinching" joined with the metaphor of the mirror to become a core of the East Asian political tradition.

The English candor appeared in the early seventeenth century, borrowed directly from the Latin candor, whose original meaning was "radiance, dazzling whiteness, pure white." The root is the verb candere — "to shine, to blaze, to glow white." From the same root come candle, candidate (in ancient Rome those standing for office wore pure-white togas), and incandescent ("glowing white, blazing"). The shift in this word's meaning is fascinating. According to the OED, when it entered English in the late sixteenth and early seventeenth centuries it meant "purity, freedom from stain," and from the mid-seventeenth century its meaning shifted to "frankness that conceals nothing, fairness free of bias." Physical "radiance" was transformed into moral "transparency." Francis Bacon (1561–1626), a contemporary of Shakespeare, used candor in his essays to mean "the character that judges between truth and falsehood without deceit." By the eighteenth century the word had settled firmly into its modern sense of "frank and unflinching speech and conduct."