In the course of rendering the British Cassell Dictionary of English Idioms, the writer fairly often comes across a good few idioms which are hard to comprehend or render. It is necessary for him to employ many a translation technique to work out a solution for them. In the present article, he cites a great number of concrete examples to illustrate and prove the intrinsic value of the theories and guiding principles of translation put forward by Eugene A. Nida and the four circles (or layers) of meaning advocated by Geoffrey Leech.