The relation whereby one thing depicts another is important both in aesthetics and in understanding mental imagery. At first sight mere resemblance might be supposed to be sufficient. But if A resembles B then B resembles A, whereas if a picture depicts a sitter, the sitter does not also depict the picture. Depiction may therefore be more a matter of the intention of the creator, or the interpretation given to a work by the audience. This in turn raises the question of whether anything can depict anything, if it is taken to do so, or whether an element of convention constrains how works are taken.