Введение в теорию и практику перевода (на материале английского языка) - стр. 12
3. Since the phraseological stock of every language reflects the history and culture of the people speaking the language, many ideas which are common to all peoples are expressed differently in different languages: in Russian we say "когда рак на горе свистнет", while in English they say "when pigs fly", in Russian – "рыбак рыбака видит издалека", and in English – "birds of a feather flock together". Since the meaning of the first phraseological unit is in no way connected with either crayfish or pigs the lexical way of wording the idea ("something never going to happen") is of secondary importance. The main task here is to find a phraseological unit of TL expressing the same idea and belonging to the same stylistic register (стилистический регистр) as the original phraseological unit. The same is true about the second example. The complete substitution of the image does not in any way change the general meaning of the proverb. "У семи нянек дитя без глазу" is an adequate translation of the English "Too many cooks spoil the broth" because of complete coincidence of sense and stylistic reference.
So in all the cases when phraseological units of SL have no equivalents in TL, and in TL there are no expressions based on the same image, complete substitution of image (i.e. use of phraseological analogues) is recommended.
4. In SL there may exist phraseological units that have neither equivalents nor analogues in TL. The idea expressed in these units has no fixed expression in TL. If the image underlying them is not transparent and loan translation is impossible, such phraseological units are translated descriptively, i.e. by free phases which are neither phraseological nor figurative: "get the right (wrong) end of the stick" – "оказаться в выгодном (невыгодном) положении", "in a whole skin" – "благополучно, без повреждений", etc.