From Paul Phillips:

I see adjoint functors.

How often do you see them?

All the time. They’re everywhere. pic.twitter.com/6PkGJ9wP4A

— Paul Phillips (@contrarivariant) May 27, 2017

Mashup of Saunders Mac Lane’s quip “Adjoint functors arise everywhere” and Haley Joel Osment’s famous line from Sixth Sense.

**Related**: Applied category theory

(My dissertation supervisor and I used to describe elegant connections as “adjunctive”. In 1998 I drafted a koan…)

A student asked Mac Lane, “Do categories have Buddha nature?”

Mac Lane constructed an adjunction between mathematics and religion. Mac Lane then asked the student, “Does category theory have Buddha?”

The student was enlightened.