What is the meaning of the phrase "every dog has its day"?

YARNLADY is happy everyday May 31st, 2007 "The most common interpretation of this expression is that any given person's moment of glory is inevitable. This proverb was used in Shakespeare's "Hamlet" (Act 5, Scene 1) HAMLET: Let Hercules himself do what he may, The cat will mew and dog will have his day." In "Wise Words and Wives' Tales: The Origins, Meanings and Time-Honored Wisdom of Proverbs and Folk Sayings Olde and New" by Stuart Flexner and Doris Flexner (Avon Books, New York, 1993), the history of this proverb is traced to the medieval Dutch scholar Erasmus. Erasmus said that in 405 B.C. Euripides, a Greek playwright, was mauled and killed by a pack of dogs loosed upon him by a rival. So the saying is usually taken as "even the most lowly person will at some time get revenge on his oppressor, no matter how powerful the man may be." Plutarch, a Greek biographer, recorded the proverb for the first time in 'Moralia' (A.D. 95): 'Even a dog gets his revenge'. Richard Taverner ... more