Optics by Isaac Newton is a groundbreaking book where Newton explains how light works. He shares his experiments with prisms, showing how white light can split into a rainbow of colors and then combine back into white light. Newton also discusses how light behaves when it reflects, refracts, and creates patterns like rainbows and shadows. The book is full of observations and theories that laid the foundation for our understanding of light and color today. It's a key work in the history of science, making complex ideas about light easier to understand.