 There are a great many other sorts of incomplete symbols besides descriptions. There are classes… and relations taken in extension, and so on. Such aggregations of symbols are really the same as what I call “logical fictions”, and they embrace practically all the familiar objects of daily life: tables, chairs, Piccadilly, Socrates, and so on. Most of them are either classes, or series, or series of classes. In any case they are all incomplete symbols, i.e. they are aggregations that only have a meaning in use and do not have any meaning in themselves. (Russell 1918, 122)