" Since a value is that which one acts to gain and/or keep, and the amount of possible action is limited by the duration of one’s lifespan, it is a part of one’s life that one invests in everything one values. The years, months, days or hours of thought, of interest, of action devoted to a value are the currency with which one pays for the enjoyment one receives from it. "

― Ayn Rand , Introduction to Objectivist Epistemology