All right, I'll bite, I don't mind.
What about when the light is acting like a wave?
Rayleigh, Jeans
had not the means
Einstein didn't want 'em
It took Neils Bohr
and several more
to figure out the quantum...
(Hazy quote from memory, from (I believe) an old article in Physics Today...)
Cheers and Merry Christmas!
Merry Christmas, too!