Who said “In this theater of man's life, it is reserved only for God and angels to be lookers-on.”?

“Leisure is the mother of Philosophy.”

“It is already possible to imagine a society in which the majority of the population, that is to say, its laborers, will have almost as much leisure as in earlier times was enjoyed by the aristocracy. When one recalls how aristocracies in the past actually behaved, the prospect is not cheerful.”

“The end of labor is to gain leisure.”

“Cultivated leisure is the aim of man.”

“Leisure is the exultation of the possible.”

“Rest satisfied with doing well, and leave others to talk of you as they will.”

“Strength of mind rests in sobriety; for this keeps your reason unclouded by passion.”

“Above the cloud with its shadow is the star with its light. Above all things reverence thyself.”

“Concern should drive us into action and not into a depression. No man is free who cannot control himself.”

“Friends are as companions on a journey, who ought to aid each other to persevere in the road to a happier life.”

“If there be light, then there is darkness; if cold, heat; if height, depth; if solid, fluid; if hard, soft; if rough, smooth; if calm, tempest; if prosperity, adversity; if life, death.”