Other renderings give 'Birds roost with their own kind, so honesty comes home to those who practice it' ( New Revised Standard Version Catholic Edition, 1989), 'Birds nest with their own kind, and honesty comes to those who work at it' ( New American Bible Revised Edition, 2011), and so forth. Richard Challoner's 1752 version of the Douay–Rheims Bible translates this asīirds resort unto their like: so truth will return to them that practise her. Verse 27:9 of this Greek version of Sira's Hebrew original is This was translated into Greek sometime after 117 BC (probably), and it is this Greek version that has commonly been used, even in the Septuagint used by diaspora Jews. The first known written instance of metaphorical use of the flocking behavior of birds is found in the second century BC, where Ben Sira uses it in his apocryphal Biblical Book of Ecclesiasticus, written about 180–175 BC. This behavior of birds has been observed by people since time immemorial, and is the source of the idiom ('of a feather' means 'of the same plumage,' that is, of the same species).

In nature, birds of the same species in flight often form homogeneous groups for various reasons, such as to defend against predators.

3 Equivalent phrases in other languages.

Flock and feathers