Actually it’s the other way round: mostly nigredo in alchemy, as it’s by far largest part, and in physics he literally invented the rainbow.
He didn’t “invent” the rainbow. He stole it from God.
That’s intellectual property, copying is no theft when credit is given, and sure he did give all the due credit to God and them some more.
Newton is so strongly the posterboy for how you can be brilliant in one area, and still so wrong in so many others. He spent about equal time looking at physics, alchemy and some bullshit da-vinchi code search for secrets in biblical numerology. Can you just imagine how much further he could have pushed physics and mathmatics if he hadn’t spent 2/3rds of his time chasing red herrings.
Newton was evidently searching for meaning in the universe and God, and I don’t think it was a bullshit code search. The scientific establishment back then was extricably connected to Christianity, and esoterically with alchemy. It wasn’t the scientific establishment post-Victorian as we know it now.
The Victorians popularised Utilitarianism, which cut away those elements that otherwise Newton was a part of.
