Musical tones, an engraving by the English physician, astrologer, and mystic Robert Fludd (1574-1637). Fludd's philosophy is presented in Utriusque Cosmi, Maioris scilicet et Minoris, metaphysica, physica, atque technica Historia (The metaphysical, physical, and technical history of the two worlds, namely the greater and the lesser), published in Germany in 1617.