"Sensing mana? No more correctly, brush against it?"
Cain was certainly perplexed by this phrase. It was the first step he had to take if he wanted to become a runecrafter. He wouldn't be able to create a link between mana that was present in the atmosphere if he couldn't brush against the flow patterns in the spiritual realm of reality. That was what was stated in the tome.
However, although he could sense mana during a battle and create all sorts of skills and spells, he had no idea how to do that about runecrafting. To him, mana was just a vague concept. All he knew was that it was needed to activate skills and spells.