Musonius Rufus, like a lot of the Stoics, was a strict man. He was strict with himself. He was strict with his students. He believed in hard work, he did not ease up, just because other people did or because he had been successful.
A friend would describe one evening, when in Athens, when they were enjoying the Saturnalia—quite pleasantly, in fact: “We did not, however, let our minds go lax,” he wrote, “for, Musonius says, ‘to let one’s mind go lax is, in effect, to lose it.’”
Unfortunately, this is a common belief, not just among the Stoics. People think they are too important, the stakes of their work are too high, that there is not a minute to lose. So they never relax. They never shut off their minds. They never check out, or let go. And far too often they end up losing it.
“The mind must be given relaxation,” Seneca said, “it will rise improved and sharper after a good break. Just as rich fields must not be forced… so constant work on the anvil will fracture the force of the mind.”
All muscles need rest. The brain is no exception. Fields must be alternated. Computers must occasionally be shut down or rebooted. To not do this is to risk injury, poor yields, or damage.