Board Thread:Questions and Answers/@comment-27973159-20160313215228/@comment-11051098-20160313220535

We already know that he must absorb souls (or at least souls infused with fragments of his own soul) in order to prevent reverting back to a state of having no senses.

I imagine that this works in the way that he somehow converts all the souls into pure power or something like that, continuously increasing his own power while also keeping himself in a state of having all of his senses and such.