Rack one’s brains

When we rack our brains, it means we stretch them mentally and in this sense it is a figurative allusion to the rack, the gruesome medieval torture device on which people were ‘racked’ or stretched, sometimes, until their limbs were dislodged from their sockets. It is hardly surprising that the word rack in this sense became closely associated with both physical and mental pain. Many things were racked before William Beveridge first used the expression rack one’s brains in his Sermons published c. 1680. In 1602, for example, Shakespeare used the word rack in relation to time, where Sebastian in Twelfth Night Act V, Scene I, says, “How have the hours racked and tortured me!”