Terrified, he at last returns, with relief, to mindlessness.
Bethink you, have there not been days, aye and months, in your own life when you would have rejoiced to sleep in mindlessness?
c.1400, "unmindful, heedless, negligent," from mind (n.) + -less. Related: Mindlessly; mindlessness. Old English had myndleas "foolish, senseless."