 The Aczel system is distinct from the Boffa system in having fewer ill-founded objects. For example, the Aczel theory proves that there is just one object which is its own sole element, while the Boffa theory provides a proper class of such objects. The Aczel system has been especially popular, and we ourselves witnessed a great deal of enthusiasm for this subversion of the cumulative hierarchy. We are doubtless not the only ones to point this out, but we did notice and point out to others that at least the Aczel theory has a perfectly obvious analogue of the cumulative hierarchy. If \(A_{\alpha}\) is a rank, the successor rank \(A_{\alpha +1}\) will consist of all those sets which can be associated with graphs \(G\) with a selected point \(t\) with all elements of the field of \(G\) taken from \(A_{\alpha}\). The zero and limit ranks are constructed just as in ZFC. Every set belongs to an \(A_{\alpha}\) for \(\alpha\) less than or equal to the cardinality of its transitive closure. (It seems harder to impose rank on the world of the Boffa theory, though it can be done: the proper class of self-singletons is an obvious difficulty, to begin with!).