To “lose your marbles” means to go crazy. Once you lost your marbles, your sanity is far gone. But that seems like an odd association – what do marbles have to do with sanity?
There are a number of different possible origins of the phrase. But what was the first use? The meaning likely comes from the connection with a child losing his toys, such as his marbles, and not being happy about it. In 1886, the St. Louis Globe-Democrat published this sentence in an excellent summation of the connection of ideas: “He has roamed the block all morning like a boy who has lost his marbles.”
In the late 1800’s to “lose your marbles” meant getting angry. For a while “marbles” danced the line between meaning “anger” and “sanity”. One interesting note is that in the 1920’s, a person who had lost control had “let his marbles go with the monkey”, a phrase that came from a story about a boy whose marbles were taken by a monkey.
The meaning changed by the 20th century, however. In 1898 The Portsmouth Times published this line: “Prof. J. M. Davis, of Rio Grande college, was selected to present J. W. Jones as Gallia’s candidate, but got his marbles mixed and did as much for the institution of which he is the noted head as he did for his candidate.”
And in 1927, American Speech sealed the deal by defining losing your marbles as “Marbles, doesn’t have all his (verb phrase), mentally deficient.”