Kozma Petrovich Prutkov (Russian: Козьма́ Петро́вич Прутко́в) is a fictional author invented by Aleksey Konstantinovich Tolstoy and his cousins, three Zhemchuzhnikov brothers, Alexei, Vladimir and Alexander, during the later part of the rule of Nicholas I of Russia.
The four distinguished satirical poets used this pseudonym as a collective pen name to publish aphorisms, fables, epigrams, satiric, humorous and nonsense verses in the 1850s–1860s, most notably in the literary magazine "Sovremennik" (The Contemporary).
According to the Biographical data on Kozma Prutkov, Prutkov was born on April 11, 1803 and died on January 13, 1863. He worked for the government of the Russian Empire his entire adult life, and in 1820 entered military service as a Hussar only for the uniform. He worked at the Assay Office (Пробирная Палата) from 1823 until his death, ending up as its director.
- "Throwing pebbles into the water, look at the ripples they form on the surface. Otherwise this activity will be an empty amusement."
- "Where is the beginning of the end that comes at the end of the beginning?"
- "If you have a fountain, shut it down. Let even a fountain have a rest."
- "If you see a "buffalo" sign on an elephant's cage, do not trust your eyes."
- "If ever asked: What's more useful, the sun or the moon, respond: The moon. For the sun only shines during daytime, when it's light anyway, whereas the moon shines at night." (This aphorism is usually associated with Mullah Nasruddin.)
- "Nobody can take hold of limitless."
- "When it concerns art, every tailor has views of his own."
- "Every expert is like a gumboil: his fullness is one-sided."
- "Not every general is stout by nature."
- "Snap a mare on the nose and she will flap her tail."
- "God placed death at the end of life to give us time to prepare for it."
- "If you want to be happy, be so." (Frequently misattributed to Count Leo Tolstoy.)
- "If you want to be handsome, enroll in the Hussars."
- "Diligence overcomes everything!"
- "Sometimes, diligence can overcome even the reason."
- "How pathetic is any constitution at sight of well-kept ammunition!"
- "Don't tell jokes to the ladies, for these jokes are stupid and obscene"
- "Even an oyster has enemies" - often quoted as "Even oysters have enemies", e.g. Barbara Heldt Monter: Kozma Prutkov - the Art of Parody. Mouton 1973. p. 58 or Jack Nicholson at the 2010 AFI Life Achievement Award ceremony for Mike Nichols (without naming the author Kozma Prutkov) 
- (Original Russian: И устрица имеет врагов! - No. 86 in: Плоды раздумья - Мысли и афоризмы)