Have you ever gone through plastic surgery? Let's say facial plastic surgery. You knew you would become more handsome(maybe), you wanted to become more handsome(certainly), but the very skilled doctor just had to go about the job with no anesthesia. And even then, you knew that powering through the experience would make you more handsome(maybe… if you survived).
When Mountain powered through the pain, he got a more intuitive understanding of it.
Indeed, gritting his teeth worked, and he felt those same cells, which used to be the end point of the energy absorbed during evolution, be the source of the pain.
Feeling things more closely, he finally saw the difference.
