homo sum humani a me nihil alienum puto

I am a human being; nothing human is strange to me

Notes

From Terence, Heautontimoroumenos. Originally "strange" or "foreign" (alienum) was used in the sense of "irrelevant", as this line was a response to the speaker being told to mind his own business, but it is now commonly used to advocate respecting different cultures and being humane in general. Puto (I consider) is not translated because it is meaningless outside of the line's context within the play.