Through his scientific careers, Isaac Newton's empirical work was inseparable from his alchemic work and considerations. He was known to consider and on occasion posit Hermetic ideas and occult forces as the motivation for attraction between particles. According to Westfall's biography of Newton and Edelglass' book Matter and Mind: Imaginative Participation in Science, Newton most likely would not have developed any of his theories on gravity had in not been for his belief in Hermetic forces over distance.
Newton was particularly alchemistic in his studies on light and optics, in his works Hypothesis of Light (1675) and Opticks (1704). His answer to the question of whether light was a wave or particle was that light either cyclically transmutated across the dividing line or was particles ("subtler corpuscles") but did something akin to transmutation through the particles it illumined.
According to Westfall's biography of Newton (1983) and Edelglass' book Matter and Mind: Imaginative Participation in Science (1991), Newton most likely would not have developed any of his theories on gravity had in not been for his belief in Hermetic forces over distance. It was defense against criticism of this belief that he penned his phrase "Hyptheses non fingo", in the second edition of his Principia (1713). "I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction."
In his work about Newton, "Newton, The Man", John Maynard Keynes wrote, "Newton was not the first of the age of reason: He was the last of the magicians."
In other news:
Aristotle was the de facto founder of alchemy, far before there was alchemy.
Alchemy fully came together in Alexandria in Hellenistic Egypt.
Alchemy was instrumental to advances made by Islamic scientists, astronomers, and mathmeticians during Europe's Middle Ages.
Other intersting know alchemists include Carl Jung, August Strindberg, Avicenna, Gerald FitzGerald the "Wizard Earl" of Kildare, Cornelis Drebbel, Agrippa, Holy Roman Emperor Rudolf II, Rudolf Steiner, and Tycho Brahe.