The idiom that expresses “birds of a feather flock together” isn’t expressed so vividly in Chinese as it is in English, but it is a very useful and often-used phrase. Surprise your Chinese friends. It is expressed as wùyǐleìjù ( 物以类聚): wù “things,” yǐleì “the same category,” jù “get together.” If you are learning Chinese and are enthusiastic, find some other enthusiastic birds to flock with. You will learn a lot faster. You’ll find it flocking easy.