Teach fish how to swim

Teach fish how to swim is an idiomatic expression derived from the Latin proverb piscem natare doces. The phrase describes the self-sufficiency of those who know better how to do everything than the experts. It corresponds to the expression, "teaching grandmother to suck eggs".^[1] Erasmus attributed the origins of the phrase in his Adagia to Diogenianus.^[2]

A corollary idiomatic phrase is part of common usage in Chinese "班門弄斧"^[3]

^ Belton, John Devoe (1891). "A Literary Manual of Foreign Quotations, Ancient and Modern". New York: G. P. Putnam. p. 151. Retrieved 11 April 2018.
^ Erasmus, Desiderius (2005). Grant, John N. (ed.). Collected Works of Erasmus. Vol. 35: Adages Ill iv 1 to IV ii 100. Translated by Drysdall, Denis. Toronto: University of Toronto Press. p. 134. ISBN 0802036430. Read online: Erasmus (2005), p. 134, at Google Books; compare Ἰχθὺν νηχέσθαι διδάσκεις
^ Muehl, Louis Baker et al. (1999). Trading Cultures in the Classroom: Two American Teachers in China, p. 18, at Google Books; 班门弄斧: display one's slight skill before an expert e.g. 在你面前班门弄斧,太不好意思了 (I'm making a fool of myself trying to show off before an expert like you)

[1] Belton, John Devoe (1891). "A Literary Manual of Foreign Quotations, Ancient and Modern". New York: G. P. Putnam. p. 151. Retrieved 11 April 2018.

[2] Erasmus, Desiderius (2005). Grant, John N. (ed.). Collected Works of Erasmus. Vol. 35: Adages Ill iv 1 to IV ii 100. Translated by Drysdall, Denis. Toronto: University of Toronto Press. p. 134. ISBN 0802036430. Read online: Erasmus (2005), p. 134, at Google Books; compare Ἰχθὺν νηχέσθαι διδάσκεις

[3] Muehl, Louis Baker et al. (1999). Trading Cultures in the Classroom: Two American Teachers in China, p. 18, at Google Books; 班门弄斧: display one's slight skill before an expert e.g. 在你面前班门弄斧,太不好意思了 (I'm making a fool of myself trying to show off before an expert like you)

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