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[Ancora imparo.]

Michelangelo (1475-1564) Italian artist, architect, poet [Michelangelo di Lodovico Buonarroti Simoni]

(Attributed)

Also rendered Anchora imparo. This is often described as a daily mantra of Michelangelo's. This association can be traced to Richard Duppa, The Lives and Works of Michael Angelo and Raphael (1806) [tr. Hazlitt]. Duppa misattributed to Michelangelo a drawing by Domenico Giuntalodi, which included the saying. The phrase itself was popular during the 16th Century.

While there's no indication that Michelangelo did not say this, or agree with the sentiment, it does not seem to have been solidly cited to him, or shown to be a personal motto, let alone being original to him.

More discussion: Michelangelo - Wikiquote.