What had helped Raistlin in the Tower of High Sorcery?

The thing that had helped Raistlin in the tower of high sorcery was a voice that he had heard. Although he had thought he was alone, there was a voice within his mind that he had heard, but never could identify and yet seemed to know. This voice had helped him in the Tower, and had helped him since, although Raistlin had always connected the voice with the Tower.