Its no accident that the main function of the sun at the center of our solar system is to provide light. Light is what drives life. Its hard to imagine our world and life without it.

The sensing of light by living things is almost universal. Plants use light through photosynthesis to grow. Animals use light to hunt their prey or to sense and escape from predators. Some say that it is the development of stereoscopic vision, along with the development of the large human brain and the freeing of hands from locomotion, that have allowed humans to evolve to such a high level.

In this edition of HowStuffWorks, you will learn about the amazing inner workings of the human eye!