He looks intense as fuck. The cat looks like they'd open the door high on catnip and invite you in for a glass of milk when you were just there to drop off the mail.
He was just bummed they wouldn't give his cat a noble laureate for helping him realized language is also an expectation of received meaning and not just intended meaning.
To honour his work, in Mérida, Yukatán, Mexico, a memorial has been erected modelled based on that photograph.