What did George Fox mean by "inner light" and how does it differ from the mainstream "illumination of the scripture" by the Holy Spirit?

I went down a rabbit fox hole reading the original sermons of the founder of the Quakers (pun intended). I was not that familiar with George Fox and I found it very illuminating to read his works directly. He certainly had a lot to say about the "inner light". At first I just thought he was meaning the illumination of scripture by the Holy Spirit whereby our faith is lit and kindled. However as I kept reading different parts of his works he simply would not stop talking about this "inner light" and in fact barely talked about anything else. In the end, I grew to dislike the phrase. He also seemed quite envious of leaders in the other churches. But that’s just my initial impression. I began to realize it is not the illumination of scripture but something else that actually **put his mind in anger against the written word in some strange way** that is hard to pin down. The difficulty is that he correctly identified the difference between the inner life of a Christian as described in the scripture and the mere external form, but from there he amplified the difference into a much bigger issue and kept ranting about the "word" of scripture not being the Word (the Son), as though they can’t both be the Son in different senses. It is very difficult sometimes to read in between the lines to fully unravel the threads and I don’t have the time and have already lost interest to work out a fuller understanding. Does anyone actually know what George Fox meant by "inner light" and how it is different from the mainstream idea of the inspiration of the Holy Word and the illumination of the scripture by the Holy Spirit?