The art of resting is a part of the art of working. A man who is tired and greatly in need of rest cannot do any good work. We are all familiar with those terrible mornings after sleepless nights when our brains refuse to function. It would be useless then to attempt to apply the principles of the art of working. Those principles presuppose mind and body to be in good condition. The human organism cannot live without alternating work and rest.
Un Art de Vivre (The Art of Living) (1939) - The Art of Working