A professor is someone who talks in someone else's sleep.

The quip reduces “professor” to a comic image of one-sided speech delivered to an unresponsive audience: the lecturer talks, but the listener is effectively asleep. It satirizes academic authority and the ritual of instruction when it becomes detached from genuine attention or dialogue. By shifting the cliché of “talking in your sleep” onto the professor, the line also hints at how teaching can feel like speaking into a void—knowledge performed rather than exchanged. As an Auden-like epigram, it works by deflating a revered role with a sharp, memorable reversal.