I came across this quote of Einstein’s while reading the book Catching the Light, The Entwined History of Light and the Mind, by Arthur Zajonc. (Prof. Zajonc is a Prof. of Physics at Amherst College and studies quantum optics.)
All the fifty years of conscious brooding has brought me no closer to the answer to the question, What are light quanta? Of course every rascal thinks he knows the answer, but he is deluding himself.

I also found this very nice web page that explains with graphics in simple terms the wave-particle duality of light.

[/caption]” target=”_blank”>Einstein Explained – Explore – The Lab – Australian Broadcasting Corporation’s Gateway to Science

Zajonc asks the question:

What is the nature of this invisible thing called light whose presence calls everything into view – excepting itself?

It is something interesting to ponder. Please comment if you please.