A mind meld is a technique for sharing thoughts, experiences, memories, and knowledge with another individual, essentially a limited form of telepathy. It usually requires physical contact with a subject, though instances of mind melds without contact have been seen. When first depicted in the TOS episode "Dagger of the Mind", the procedure was said to require several moments of intense concentration and preparation. However, subsequent episodes show contact between minds occurring almost immediately. Although most often seen done with humanoids, mind melds can be performed with members of other species. Spock even once successfully mind melded with a machine and was able to establish telepathic contact with the mechanical probe V'ger. Mind melds can be used both to erase and restore memories; Spock performs each of these on Captain Kirk during TOS 's third season. A mind meld was even used to rejoin Spock's katra with his physical body. Mind melds can also allow more than one mind to experience memories and sensations, and sometimes even interact with the memories. Some species are able to resist mind melds.