He only understands that he has left out love in his aim, and therefore failed.

He does not give up the notion of attainment upon earth.

He cannot lose the first imprint of his idea of himself--his lonely grasp of the whole of Knowledge.
The next two parts of the poem do not strengthen much the main thoughts.

Paracelsus tries to work out the lesson learnt from Aprile--to add love to knowledge, to aspire to that fulness in God.

But he does not love enough.