 (c) The third and final reading claims that while Nāgārjuna undoubtedly also wanted to assert the existential dependence of the properties ‘being a cause’ and ‘being an effect’ on each other he moreover made the claim that not only the particular object which is the effect needs the cause for its existence, but the cause also needs the effect. Such a reading can be supported by considering an entire causal field, that is the cause together with the necessary background conditions, rather than just particular causes. A causal field is a cognitive artefact, a collection of objects assembled with the sole purpose of explaining why a particular effect came about. Divorced from this explanatory role there is no reason for introducing the concept at all. We might therefore want to argue that the causal field also depends for its existence on the effect it produces. This is of course not to say that every member of the causal field existentially depends on the effect they jointly bring about: the spark, petrol, and so forth would still exist, even if they for some reason did not manage to bring about an explosion. But the collection only exists if there is some effect it causes. Whether we want to argue that a causal field depends for its existence on the effect it brings about is intimately connected with our view of the existence of collections. We might either think that whenever the are some objects there is the collection of those objects. Or we might deny that every arbitrary assembly of objects constitutes a collection. We would then argue that for some objects to form a collection there must be something which makes them hold together as a collection, for example that they all exemplify a property, or that they were put together for a specific purpose. If we adopt the first view of collections then clearly a causal field will only depend notionally on its effect, since ‘being a causal field bringing about that effect’ is only one way in which we can refer to the pre-existent collection that contains all the elements of the causal field, but not anything which brings it about. Adopting the second conception, however, it may be the case that the only thing that binds all the members of the causal field together is that they are considered to be the things that jointly bring about a particular effect. In the absence of this effect the collection disintegrates and ceases to exist.