In the analogy with a video projector, having a nervous system is like having a lens in the projector. Without the lens there is still light on the screen, but the images are much less sharp. In philosophical circles the idea that consciousness is in everything is called panpsychism , from the Greek pan , meaning all, and psyche , meaning soul or mind. Unfortunately, the words soul and mind suggest that simple life forms may possess qualities of consciousness found in human beings. Whatever name this position is given, its basic tenet is that the capacity for inner experience could not evolve or emerge out of entirely insentient, non-experiencing matter.
Experience can only come from that which already has experience.
Therefore the faculty of consciousness must be present all the way down the evolutionary tree. Even some single-celled organisms are sensitive to physical vibration, light, and heat. It may be a billionth of the richness and intensity of our own experience, but it is still there. Some argue this implies that rocks perceive the world around them, perhaps have thoughts and feelings, and enjoy an inner mental life similar to human beings. This is clearly an absurd suggestion, and not one that was ever intended.