To Truly Understand a Rainbow

White light was one simple, uniform, and solid thing

Step 1: The chapter explains the old belief about white light before Newton's discovery. Step 2: It says Aristotle had claimed that white light was 'one simple thing — uniform and solid.' Step 3: Scholars accepted this belief for a very long time without questioning it. Step 4: This is exactly what Newton set out to challenge. Step 5: The idea that white light contains all colours was actually Newton's discovery, not Aristotle's belief.

Colour was a mixture of light and darkness

Step 1: Robert Hooke was a scientist who was a contemporary of Newton. Step 2: The chapter tells us Hooke 'continued to insist that colour was a mixture of light and darkness.' Step 3: He even made his own colour scale where red was white light with little darkness, and blue was more darkness blocking the light. Step 4: Newton disagreed with this view. Step 5: The idea of colour being caused by raindrops or prisms alone was not Hooke's theory.

He observed that black and white seen from a distance appeared grey, not colourful

Step 1: Newton questioned Aristotle's and Hooke's theory by using a simple observation. Step 2: He pointed out that a white page with black writing, when seen from far away, blended into grey. Step 3: It did NOT appear in colour. Step 4: This proved that mixing black and white does NOT produce colour. Step 5: This simple logical argument helped Newton decide to challenge the accepted theory and conduct his own experiment.

Twenty-two feet

Step 1: The chapter describes Newton setting up his experiment carefully. Step 2: He worked in his study upstairs and wanted more accurate results. Step 3: The text says he 'positioned the prism at the far wall so that it was twenty-two feet from the window.' Step 4: He believed that moving the prism farther away would give better and more accurate results. Step 5: Other scientists had kept the screen close, but Newton understood that distance mattered.