It should be remarked in passing that Zermelo doesn't deal specifically with the Burali-Forti paradox either, for the simple reason that it cannot be properly formulated in his system, since it deals either with well-orderings generally or with the general concept of ordinal number. We will come back to this below. However, assuming that the known paradoxes can be avoided, another question comes to the fore: if the Separation Axiom is to be the basic principle for the workaday creation of sets, is it adequate? This question, too, will be taken up later.