Difficulty is a severe instructor, set over us by the supreme ordinance of a parental Guardian and Legislator, who knows us better than we know ourselves, as he loves us better too. Pater ipse colendi haud facilem esse viam voluit. He that wrestles with us strengthens our nerves, and sharpens our skill. Our antagonist is our helper.
Edmund Burke, Reflections on the Revolution in France (1790), Volume iii, page 453.