Numerous other philosophers and scientists, including Isaac Newton (1704), Erasmus Darwin (1790) and Wilhelm Wundt (1874) may have referred to synesthesia, or at least synesthesia-like mappings between colors and musical notes.
The passage suggests that several prominent figures in the history of philosophy and science, including Isaac Newton, Erasmus Darwin, and Wilhelm Wundt, might have been aware of or explored the concept of synesthesia, which involves experiencing color and sound as intertwined sensations.