When light, sound, food, touch etc contacts the body, the corresponding (eye, ear, tongue, etc..) sense organs pick up these stimuli, and the electrical stimulus is sent via a nerve to the brain. The brain then unpacks that electrical signal, much like a TV unlocks the electrical signal of cables, and converts it into an image. These ‘electrical images’ are presented to us much like ghosts or echoes of some event which happened a few moment ago. i.e. we cannot ever capture the true ‘present moment’ and we are alive slightly to the past. Not being in the ‘true’ present moment is never a problem, as we live in our created bubbles, as does everyone else, thereby ‘in-sync’ with everything.
Even though we think we are aware of our surroundings, what we are truly aware of, is the mind created ‘world’. The world which is ‘out-there’ sends a signal internally, so this gives rise to the process of creating the world. That is, the process isn’t entirely divorced of some external reality, but causes and effects starting from this ‘external world’ end up giving rise to a reality inside. It wouldn’t be taking it too far to say that external stimuli gives rise to the Mind. The mind only comes into existence, if it is stimulated either externally from the external environment or internally from memories, which are also derived ultimately from the external environment, and reactions to it.