The basis of many phraseological units in the Russian language are sayings and sayings. So, the stable expression "like water off a duck's back" comes precisely from oral folk art, although it also has a very logical justification and interpretation.
The origin of the expression "like water off a duck's back." It is believed that the expression "like water off a duck's back" comes from an old conspiracy that was used to treat various diseases. Rural healers, and often sorcerers, spoke water, throwing a coal into it, and after that they poured water over a sick person with the words "like water off a duck's back, so thinness from him (pronounced the name of a person)." Often, parents, bathing their children, repeated this proverb, so that not a single attack would stick to the child. At the same time, "thinness" is not synonymous with harmony, it means just a disease, ailment. Interestingly, in some regions of Russia, instead of the word "goose", "gogol" was used, although in fact this is the name of another waterfowl - a diving duck. But in this case, the generalization does not change the meaning of the folk saying.
The meaning of the phraseological unit "like water off a duck's back." Over time, the second part of the popular conspiracy was forgotten, and now the phraseologism "like water off a duck's back" is used in relation to a person who gets away with everything quickly and without consequences, no matter what actions he does. Such proposals have a negative connotation, emphasize a disapproving attitude towards a person. Sometimes, however, the phrase "like water off a duck's back" is used if someone is not taken by difficulties and troubles, as if the person had not undergone trials.
Geese and water. It is worth noting that water easily flows not only from geese, but also from other waterfowl, such as ducks and swans. The thing is that all birds have a coccygeal gland (it is also called the tail gland at its location). It secretes a special secret that is released outside and spreads over the entire surface of the body. In waterfowl, this gland is especially developed, and the secreted oily substance soaks the feathers and protects them from getting wet. That is why it is enough for a goose to get out of the water, dust it off, and it will be completely dry again.
The expression "like water off a duck's back" in Russian literature. In folk phraseology, the goose personifies stupidity and stubbornness, this bird often appears in proverbs and sayings. The expression "like water off a duck's back" is quite often found in Russian literature, especially in the works of authors who gravitated towards folk literature and wisdom. So, Ivan Sergeevich Turgenev used it in the novel "The Noble Nest", and Lev Nikolaevich Tolstoy in the trilogy "Walking through the agony". Also, phraseological units are used in the play by Nikolai Vasilyevich Gogol "The Marriage".