Yup, from what I’ve read he spent most of his time on the Bible and Alchemy. Remember that alchemy was essentially chemistry in those days, not a seperate science. I personally think Newton got interested in optics because of the Biblical account of the the creation of the rainbow after the flood. It’s the one example I know of where God made a permanent change in natural laws after creation, and I think it caught Newton’s attention. Personal theory of mine, very few facts to support it, which is just how I like I like my theories.
Plausible enough, to me.
Thx.