teach [OE] In Anglo-Saxon times to teach was at first ‘to present’ or ‘to point out’, although the idea of instructing someone soon developed. The word shares an ancient root with *token. The proverb don’t teach your grandmother to suck eggs has been in use since the 18th century as a caution against offering advice to someone wiser and more experienced than yourself. Sucking eggs was something thieves did on a farm, as to suck the centre from an egg on the spot is the quickest and safest way to eat it surreptitiously. Many similar expressions have been invented down the years, such as don’t teach your grandmother how to steal sheep, with the shared idea that an older person knows a lot more about cunning dodges than you do. The assumption here is that the longer experience of the older person brings wisdom, but the saying you can’t teach an old dog new tricks [M16th] associates the knowledge of years with rigidity, and an inability to take new things on board.