In contrast the thinking of his day, Johannes Muller held that each nerve leads to one sensation only. The message nerves carry is not determined by the stimulation (visual, auditory or tactile) but by the brain. If the eye is stimulated by touch (pressure), electricity or by light waves, the result is a visual sensation.
This is the Muller who lived from 1801-1858). The other Muller (with dates of 1752-1809) is a Swiss historian. Keep this in mind when you watch this video on Psychology and Experimental Physiology.