Tow-kath was a Vulcan technique which was a trance-like state which badly injured individuals entered into which led to their bodies going dormant in order to allow them the chance to repair any damage at peak efficiency. This was a learnt skill and not achieveable by simple instinct alone. Once entered into, the Vulcan had to fight in order to break the trance with this attempt often leading to the individual suffering from sudden, wrenching pain as a result.
In 2248, Spock was shot by a Marathan neural disruptor which forced him to enter Tow-kath until he was rescued by his family. Following that moment, he once again entered into Tow-kath to give time for healing and to allow his strength to return to him as he succumbed to a healing fever. Amongst the dreams he encountered in this state was himself on the USS Enterprise and later being on the grounds of the Vulcan Science Academy where fellow Vulcans told he that he was "Not logical. You are not logical". (TOS novel: Crisis on Vulcan)