  The third and last attempt to develop noneism is represented by a serious engagement with the notion of a “source”. As he had already discussed, a “source” is what allows us to understand the charactering properties that an item (cf. 1980, 463; 1995a). The source of Anna Karenina’s characterizing properties is Tolstoy’s Anna Karenina. In sistology, Sylvan aims at deepening our understanding of sources by admitting that not all of them are equally reliable. For instance, optical illusions teach us that visual perceptions are not always a trustworthy source for characterizing the items we see. For this reason, Sylvan suggests introducing two kinds of predicates. The first kind (call them “ordinary predicates”) tell us how items look; the second kind (call them “non-ordinary predicates”) tell us how items really are.