Though nothing suffocates humour more swiftly than a thesis, the comic muse will never lack commentators. Sooner or later, protesting our good intentions, acknowledging the futility of the enterprise, we are all drawn to this challenge: explain the joke. The need to explain becomes, indeed, an obsession rooted in our common lot, for as Bergson rightly remarks, the comic does not exist beyond the pale of what is strictly human. Together with the power of speech, the mathematical gift, the gripping thumb, the ability to make tools, humour is a specifying characteristic of humanity. For many of us, it is more than an amiable decoration on life; it is a complex piece of equipment for living, a mode of attack and a line of defence, a method of raising questions and criticizing arguments, a protest against the inequality of the struggle to live, a way of atonement and reconciliation, a treaty with all that is wilful, impaired, beyond our power to control.