 [T]he proposition “Some people have white skin” occurs in logic at best as an example, and not as the subject of a theorem, while a class of propositions, such as the class determined by the expression “Some A are B” may well be the subject of a theorem. If these classes of propositions are to be called general forms of propositions, then it is permissible to say that logic is concerned with forms rather than with individual propositions. (Actually, only the written or oral expression “Some A are B”, and not the class itself, should be called a form) (TS, §12, no. 2 [I.48]). 