A hobby has many functions. It provides relaxation, entertainment, indulgence in esoteric language and, usually, opportunities for conviviality with like-minded beings. The term as used here excludes avaricious accumulation and obsessed loners. (I once went to a convention of patience players which no one else attended.) What it is meant to cover is the sort of interest and enjoyment Michael Dummett experiences in his study of playing-cards and the games played with them.