MimmiCaroline

Light is an obvious feature of everyday life, and yet light's true nature has eluded us for centuries. Near the end of his life, Albert Einstein wrote, "All the 50 years of conscious brooding have brought me no closer to the answer to the question: What are light quanta?" We are today in the same state of "learned ignorance" with respect to light as was Einstein.
- Introduction to optics, third edition