All three levels of my chemistry classes have been learning about the dual nature of light in some form for the past week. Two of them (Honors & AP) have been learning about how Max Planck really pioneered the idea that light is not only a wave but also acts like a particle. Thing was, though, that nobody really believed him, even though he had experimental evidence. (and, as far as we know today, he was right).
He was lucky. Einstein came along a mere 5 years later... When he proposed the Photoelectric effect, he essentially confirmed what Planck had been saying all along.
I mention all this because recently I came across a quote by Max Planck that I really loved:
A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.