Sometimes the truth really does come down to a question. Is light a particle phenomenon or a wave phenomenon? Quantum physics tells us that the answer depends on which perspective you view it from. It's always one or the other, but it's the one you are looking for at that moment.
It's pretty counter-intuitive, but there's a good overview in Wikipedia: http://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality