Yoneda lemma

{{category theory}} Given a category ''C'' with an object ''A'', let ''H''^''A'' be a representable functor from ''C'' to the category of '''Sets''', and let ''F'' be any functor from ''C'' to '''Sets''', then there is a "natural" isomorphism between the set ''F''(''A'') and Nat(''H''^''A'',''F''), the set of natural transformations from ''H''^''A'' to ''F''.