We conceive actuality as in essential relation to an unfathomable possibility. Eternal objects inform actual occasions with hierarchic patterns, included and excluded in every variety of discrimination. Another view of the same truth is that every actual occasion is a limitation imposed on possibility, and that by virtue of this limitation the particular value of that shaped togetherness of things emerges. In this way we express how a single occasion is to be viewed in terms of possibility, and how possibility is to be viewed in terms of a single actual occasion. But there are no single occasions, in the sense of isolated occasions. Actuality is through and through togetherness—togetherness of otherwise isolated eternal objects, and togetherness of all actual occasions. It is my task in this chapter to describe the unity of actual occasions. The previous chapter centered its interest in the abstract: the present chapter deals with the concrete, _i.e._, that which has grown together. Consider an occasion α:—we have to enumerate how other actual occasions are in α, in the sense that their relationships with α are constitutive of the essence of α. What α is in itself, is that it is a unit of realised experience; accordingly we ask how other occasions are in the experience which is α. Also for the present I am excluding cognitive experience. The complete answer to this question is, that the relationships among actual occasions are as unfathomable in their variety of type as are those among eternal objects in the realm of abstraction. But there are fundamental types of such relationships in terms of which the whole complex variety can find its description. A preliminary for the understanding of these types of entry (of one occasion into the essence of another) is to note that they are involved in the modes of realisation of abstractive hierarchies, discussed in the previous chapter. The spatio-temporal relationships, involved in those hierarchies as realised in α, have all a definition in terms of α and of the occasions entrant in α. Thus the entrant occasions lend their aspects to the hierarchies, and thereby convert spatio-temporal modalities into categorical determinations; and the hierarchies lend their forms to the occasions and thereby limit the entrant occasions to being entrant only under those forms. Thus in the same way (as seen in the previous chapter) that every occasion is a synthesis of all eternal objects under the limitation of gradations of actuality, so every occasion is a synthesis of all occasions under the limitation of gradations of types of entry. Each occasion synthesises the totality of content under its own limitations of mode.