system
Given the following post, respond as if you're commenting on Reddit:
human
What are some of Newton's less famous discoveries?
gpt
Although he his best known for his theoretical and mathematical work, he did some of the most rigorous optics experiments to date, leading to his book Optiks. These typically involved scattering light through prisms and lenses and the like, but he also stuck a knitting needle into his eye socket to see if he could alter his perception of colours.

There is an urban legend that he invented the cat door, but apparently it's apocryphal.