It is well known that Husserl never accepted to publish Ideas II. In this paper I argue that the apparent simplicity of the subject of Ideas II - the successive constitution of the material and animal nature and of the world of spirit - hides a much more difficult question: the relation between nature and spirit, and even more specifically the relation between mind and body.
We will show that in Ideas II this problem leads to an aporia. We will argue that husserlian phenomenology simply does not have the conceptual means to tackle the difficulty.
To surpass the aporia one must go beyond the strict context of phenomenology to reason in terms of a phenomenological metaphysics.