"One cannot buy, rent or hire more time. The supply of time is totally inelastic. No matter how high the demand, the supply will not go up. There is no price for it. Time is totally perishable and cannot be stored. Yesterday's time is gone forever, and will never come back. Time is always in short supply. There is no substitute for time. Everything requires time. All work takes place in, and uses up time. Yet most people take for granted this unique, irreplaceable and necessary resource."
- Peter F. Drucker