What's the difference between i.e. and e.g.?
early 15c., "member of the ancient Roman noble order," from Middle French patricien, from Latin patricius "of the rank of the nobles, of the senators; of fatherly dignity," from patres conscripti "Roman senators," literally "fathers," plural of pater "father" (see father (n.)). Contrasted, in ancient Rome, with plebeius. Applied to noble citizens and higher orders of free folk in medieval Italian and German cities (sense attested in English from 1610s); hence "nobleman, aristocrat" in a modern sense (1630s). As an adjective, attested from 1610s, from the noun.