The History of coloured Hearing

This paper follows the stages that led to the casual discovery (in a certain way similar to a case of serendipity) of subjective synaesthesias and in particular investigates the French-Italian medical contribution, even though starting from a German academic document that is considered to be at the head of chain of references which, however, reveal themselves as a chain of equivocations (by doctors, before the historians). This investigation covers the crucial 70 years from the degree thesis of Sachs in 1812 to Pedronös article of 1882.