“But the stimulated sensation is usually colour vision. Synaesthesia, as the stimulation of one sensory perception by another is known, is not that unusual. ES is a professional musician who is able, literally, to taste what she hears. Almost every musical interval provokes a gustatory sensation in her. A major third sounds sweet. A minor third, salty. A fourth has the flavour of mown grass. Only an octave is tasteless.”