  The first two of these are matter and form, what an entity is made up from according to Aristotle’s hylomorphic  analysis. Understandably, both of them can be responsible for the  features and the behaviour of the entity they make up.  Hylomorphic  analysis, together with the separation of the material and formal  causes as distinct types, implies that if something is explicable in  terms of matter or form, explanations in terms of form will be different  in kind from those given in terms of matter.  As a rule there is a  collaboration between these causes: matter provides the potentialities  which are actualised by the form.  Accordingly, these causally  relevant entities give rise to a hierarchic structure of explanation.[5]    In order for a form to be realised, one needs to have suitable matter.   This suitable matter brings with it the features required by a given  hylomorphic composite. These features, then, are on the one hand the  contribution of the matter, and as such the matter is the (material)  cause of these features of the composite entity, whereas on the other  hand they are indispensable presuppositions for the realisation of the  form, and to that extent their presence is prompted by the  form.[6]  Such dependency relations between matter and form are labelled by Aristotle as cases of hypothetical necessity.  Aristotle sometimes illustrates his point by appealing to the matter required for the construction of a house.  If there is a house to be built, one needs building bricks, slabs, mortar, etc. Each part provides material with properties within a definite range of the sort required for a house to come into being.  A house cannot, for example, be made out of liquid water.  This sort of matter provides potentialities not suited to the form of house.