ABSTRACT
This, it will be seen, is merely a phrase indicating what is to be spoken of, not a true definition. It presupposes that every collection has some such property as that indicated-a property, that is to say, independent of the nature of its terms and of their order; depending, we might feel tempted to add, only upon their number. In fact, number is taken by Cantor to be a primitive idea, and it is, in his theory, a primitive proposition that every collection has a number. He is therefore consistent in giving a specification of number which is not a formal definition.
