“The mind is patient and adjusts itself, it likes to play; but the heart grows savage and will not condescend to play; it stifles and rushes to tear apart the nets of necessity.”

Schoolgirl
Another step (1986)

Source: Palace of Stone

Open Your Heart
Imagine Our Love (2007)

A Short History of Decay (1949)

Dialogue between Heraclitus and Democritus. Compare: "All the world ’s a stage, And all the men and women merely players", William Shakespeare, As You Like It, Act ii. Scene 7.
Bartlett's Familiar Quotations, 10th ed. (1919)

This is an anonymous modern quip which is a variant of a statement by G. Stanley Hall, in Adolescence: Its Psychology and Its Relations to Physiology, Anthropology, Sociology, Sex, Crime, Religion and Education (1904):
: Men grow old because they stop playing, and not conversely.
Misattributed

Source: Terre des Hommes (1939), Ch. IX Barcelona and Madrid (1936)
Context: Human drama does not show itself on the surface of life. It is not played out in the visible world, but in the hearts of men. … One man in misery can disrupt the peace of a city. It is another of the miraculous things about mankind that there is no pain nor passion that does not radiate to the ends of the earth. Let a man in a garret but burn with enough intensity and he will set fire to the world.

On Modern Marriage and Other Observations (1986)