While idle, it is either inactive or engaged in some non-maintenance activity. Depending upon their physical constitution and the environment in which they find themselves, all living creatures operate somewhere on a scale which extends from being nearly continuously busy at one extreme, to being nearly continuously idle at the other extreme. That is, some creatures must work very hard to stay alive, and others hardly at all. Those creatures which, even working continuously, are unable to maintain themselves, disintegrate and die. The Survival of the Idlest - Index of essays on the Idle Theory of Evolution.
Natural selection favours the idlest.
The fittest creatures are the idlest creatures, who survive to pass on their genes to subsequent generations. Human life, historically, is taken to have been hard. The uniquely human response was the development of tools. And since they expedited work, the use of these tools increased human idleness. The inherent purpose of an economic system is to free people from work.