Etymology
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Agatha 
fem. proper name, Latinized form of Greek Agathe, fem. of agathos "good, fit; gentle, noble" (of persons, opposed to kakoi), which is of unknown origin. Never a popular name in U.S., and all but unused there since 1940. The Greek adjective grew to include notions of wealthy, powerful, also "brave, good at fighting" (as qualities attributed to the Chiefs) as well as "good" in a moral sense. Also, of things, "serviceable, useful," and, abstractly, "the good."
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agathist (n.)

1816, from Greek agathos "good" (see Agatha) + -ist.

Doctor Kearney, who formerly, with so much reputation, delivered lectures in this place on the history of Rome, observed to me once, that he was not an optimist, but an "agathist"; that he believed that every thing tended to good, but did not think himself competent to determine what was absolutely the best. The distinction is important, and seems to be fatal to the system of Optimism. [George Miller, "Lectures on the Philosophy of Modern History," Dublin, 1816]
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