a writer's 'ability' [='capability', 'capacity'] 'to interest' readers
He always works 'to the best of his ability'. [=as well as he can]
Does he have the 'ability' [='authority'] 'to fire' employees?
(..) And I've nothing to kill it with? Help will always be given at Hogwarts, Harry. To those who ask for it. I've always pride of myself on my ability to turn a phrase. Words are, in my not so humble opinion... ... are most inexhaustible source of magic. Capable of inflicting (..)2011 Harry Potter and the Deathly Hallows: Part 2