From G. K. Chesterton (Essential Writings, Why I'm Not a Pagan; Orbis Books pgs. 116-117):

"...the Christian virtues of Faith, Hope and Charity are in their essence as unreasonable as they can be. As the word 'unreasonable' is open to misunderstanding, the matter may be more accurately put by saying that each one of these Christian or mystical virtues involves a paradox in its own nature... Charity means pardoning what is unpardonable, or it is no virtue at all. Hope means hoping when things are hopeless, or it is no virtue at all. And Faith means believing the incredible, or it is no virtue at all... Charity is a fashionable virtue in our time... Hope is a fashionable virtue today... But Faith is unfashionable, and it is customary on every side to cast against it the fact that it is a - paradox... Yet it is not one atom more paradoxical than Hope or Charity. Charity is the power of defending that which we know to be indefensible. Hope is the power of being cheerful in circumstances which we know to be desperate... The virtue of Hope exists only in earthquake and eclipse... Charity to the Deserving is not Charity at all, but Justice. It is the Undeserving who require it, and the ideal either does not exist at all, or exists wholly for them. For practical purposes it is at the hopeless moment that we require the hopeful man, and the virtue either does not exist at all, or begins to exist at that moment. Exactly at the instant when Hope ceases to be reasonable, it begins to be useful..."