Out of your mind

Origin

The phrase taps into the ancient understanding of the mind as a distinct, perhaps even separate, entity from the body. By the 17th century, to be 'out of one's mind' was a vivid, if metaphorical, description of someone who had lost their grip on reality, whether due to intense emotion, shock, or genuine mental affliction. It conjured an image of the very essence of reason having detached itself from the individual, leaving them incapable of sensible thought. This powerful visual metaphor transitioned from describing actual insanity to a common, emphatic exclamation of disbelief, suggesting someone's ideas are so wild they could only come from a mind that has truly gone astray.