The states of affairs are one of the basic categories of the formal ontology in the husserlian sense of this word. They are the objectiv correlates of judgements and they have an existence independent of propositions and of acts of judging. Their form is "the being-b of A". States of affairs have different properties. One of the most important is that they are bearers of ontological modalities. In this respect the analysis of the different classes of modalities needs to be completed for ontological investigations which make clear the several types of essences and the laws which are grounded in these essences.