I learned about three inventors and one invention. The inventors’ names are Johannes Kepler, Galileo Galilei, and John Napier. The invention is the slide rule. First, I learned about Johannes Kepler. He viewed the universe as an analogy of the Trinity. He developed a problem that required a new tool to solve, which required calculus to solve it. Kepler’s work inspired Newton. Second, I learned about Galileo Galilei. He was a pioneer and also controversial. He improved the telescope in 1609 and he applied mathematics to physics. He advanced the scientific method. Third, I learned about the slide rule. It became a symbol for the engineering profession by the 1950. The slide rule made it possible to do engineering. Lastly, I learned about John Napier. His greatest achievement was inventing the logarithm. He is best known for the King James version of the bible.