A thought maker is a device that is used to alter the brainwaves of a person. It can either be used by a person on themselves, or it can be used by one person to manipulate another person. In 2364, the Ferengi DaiMon Bok used a thought maker on Captain Picard as part of his plans to take revenge on Picard for the death of his son. Bok manipulated Picard into boarding the USS Stargazer, in which Picard defeated Bok's son nine years earlier, in order to have Picard attack his own ship, the USS Enterprise-D. Fortunately, Data was able to prevent Picard from attacking the Enterprise, and Riker was able to get through to Picard long enough to have the Captain destroy the thought maker. When the Ferengi found out what Bok was doing, Bok was relieved of his command. (TNG episode: "The Battle")