 The problem is insoluble, he says, unless one realizes that “there is on the one hand matter and on the other shape (or form, morphê), and the one is potentially and the other actively.” Once one realizes this, “then what we are inquiring into will no longer seem to be a puzzle” (1045a20–25). He offers the following example (1045a26–35). Suppose round bronze were the definition of ‘cloak’. If someone were to ask “what makes a cloak one thing, a unity?” the answer would be obvious. For bronze is the matter, and roundness is the form. The bronze is potentially round, and round is what the bronze actually is when it has received this form. The cause of the unity of the cloak (in this sense of ‘cloak’) is just the cause of bronze being made round. Since the cloak is something that was produced, or brought into being, there is no cause of its unity other than the agent who put the form into the matter. Bronze (the matter) is a potential sphere, and the cloak is an actual sphere. But round bronze is equally the essence of both the actual sphere and the potential one. The bronze and the roundness are not two separate things. The bronze is potentially a sphere, and when it is made round it constitutes an actual one—a single sphere of bronze.