“They say that genius is an infinite capacity for taking pains," he remarked with a smile. "It's a very bad definition, but it does apply to detective work.”

“[T]he infinite is in capacity. That, however, which is infinite in capacity is not to be assumed as that which is infinite in energy. …[I]t has its being in capacity, and in division and diminution. …[I]t is always possible to assume something beyond it. It does not, however, on this account surpass every definite magnitude; as in division it surpasses every definite magnitude, and will be less.”

“Genius is play, and man's capacity for achieving genius is infinite, and many may achieve genius only through play.”

“Why do we have such a finite capacity for pleasure but an infinite one for pain?”

“What a falsehood it is to say that genius and industry are incompatible! Does one work of genius exist that has not also been a work of labour?”

“The definition of genius is taking the complex and making it simple.”

“Genius is seldom recognized for what it is: a great capacity for hard work.”

“But he could not renounce his infinite capacity for illusion at the very moment he needed it most… he saw fireflies where there were none.”

“It is almost a definition of a gentleman to say he is one who never inflicts pain.”

“The nationalist not only does not disapprove of atrocities committed by his own side, but he has a remarkable capacity for not even hearing about them.”