All reasoning must be derived from observation and experiment.

This famous saying came from the Italian scientist Galileo Galilei.

Galileo Galilei (February 15, 1564 - January 8, 1642), Italian physicist, mathematician, astronomer and philosopher, a leading figure in the Scientific Revolution important person. Its achievements included improvements in telescopes and the astronomical observations they enabled, and support for Copernicus' heliocentric theory.

Historically, he was the first to integrate mathematics, physics and astronomy based on scientific experiments, expanding, deepening and changing mankind's understanding of material movement and the universe.

Galileo summarized the law of free fall, the law of inertia and Galileo's principle of relativity from experiments. This overturned many assumptions of Aristotle's physics, laid the foundation for classical mechanics, refuted Ptolemy's geocentric system, and strongly supported Copernicus' heliocentric theory.

With systematic experiments and observations, he overturned the purely speculative traditional view of nature, and created modern science with a strict logical system based on experimental facts.

Galileo is known as the "Father of Modern Mechanics" and "The Father of Modern Science". His work laid the foundation for the establishment of Newton's theoretical system.

Galileo advocated a research method that combined mathematics and experiments. This research method was the source of his great achievements in science and his most important contribution to modern science. Galileo believed that experience was the only source of knowledge, advocated the use of experimental-mathematical methods to study the laws of nature, and opposed the mystical speculation of scholastic philosophy. Convinced that the book of nature is written in mathematical language, only shape, size and speed that can be reduced to quantitative characteristics are the objective properties of objects. He was the first person to use telescopes to observe celestial bodies and achieve a lot of results.

Galileo played a major role in the development of natural science and worldview in the 17th century. Experimental science starting from Galileo and Newton is one of the founders of modern natural science.

This sentence means: Observation is a very important step. Galileo has always emphasized the importance of observation. Through observation, we can discover many details, from which we can discover doubts or some special phenomena. To do reasoning, you must first have an object, such as a suspected situation, or you suddenly have some ideas that need to be confirmed. Experiments are used to confirm your reasoning, so reasoning is inseparable from observation and experiment.