As far back as I can remember, I have heard Isaac Newton being referred to as a genius; yet it was not until I actually read some of the 'standard texts' of his time that I truly appreciated what Newton had accomplished. As John's father said
"It is only when you compare the nature of [the Principia] to the style and argumentation that dominated Natural Philosophy in the decades hitherto, that you truly appreciate its power.”
The Mysteries of Nature and Art, by John Bate, is one of the books that is said to have caught Isaac Newton's curiosity and fueled his desire to pursue the intellectual course he adopted. If you don't want to peruse the original manuscript, this article in the Public Domain Review will give you a pretty good insight into the mood and vocabulary that prevailed at the time.