Rene Descartes lived from 1596 to 1650. He was a French mathematician, philosopher, and anatomist. He contributed to modern ideas, mainly those associated with science, rational thought, and the scientific method. He was born in La Haye, a city in central France. His father was a lawyer and left him an annual income for life. He attended the college of Henri IV at La Fleche when he was 10, ordered by his father. Descartes left La Fleche in 1614 to study civil and anon law at Poitiers and two years later he had received the baccalaureate and licentiate degrees in law.
In 1918 he joined the army of Prince Maurice of Nassau as a volunteer. In his early life he wanted to accomplish something in life, something like a new and stable basis for all knowledge.. In 1637 he published Discourse on the Method for Conducting Ones Reason Rightly and for Searching for Truth in the Sciences which he wrote in France. This book introduced three ideas, one on optics, one on geometry, and one on meteorology. Four yeas later he wrote Meditations on First Philosophy which is his version of a unified and certain body of the human knowledge.
The Catholic and Protestant Church was angered by his book, claiming that Descartes hope was to replace the teachings of Aristotle. In 1644 he publish Principles of Philosophy which he hoped would in-fact replace Aristotles teachings. His last important work was called Passions of the Soul where he explored topics such as the relationship of the soul to the body, the nature of emotion, and the role of the will in controlling emotions. In 1649 Queen Christina of Sweden convinced Descartes that he should come to Stockholm to teach her philosophy.
On his way home from one of the queens lessons he caught pneumonia in February 1650 and after suffering for a week he died on February 11. Descartes philosophical system of thought is called “Cartesian” which was based on the idea of his statement, “I think therefore I am. ” He also made the first systematic account of mind and body relationship, and souls contact with the body. In the fields of mathematics and astronomy, he was one of the founders of coordinate geometry and a change in algebraic notation.
Also, he said that external motion affects the nerve divers, and it is because of this that he is credited with the founding of the reflex theory. He claimed that the world is created by god, and that it is made up of two substances, matter and spirit. In Descartes Treatise he first discussed specific problems in physics, including an echo, resonance and water pressure. He then considered mathematical problems such as the drawing of a tangent at an angle of 45 degrees to a curve, and set out his working of the complete equation in detail.
He then considered the problem of perfect numbers, stating his belief that he will be able to demonstrate that no even numbers are perfect except those of Euclid. He also discussed the center of gravity of a sphere, work on balances and levers, a point concerning burning glass, development of spectacles for old men, condensation and rarefaction, the law of falling bodies, and his theory of matiere subtile. Descartes invented what we now call Cartesian coordinates, or the system by which we can graph mathematical functions in two-or three-dimensional space.
So, all of those problems you have been working in algebra are his fault. It is interesting to consider how Descartes came to develop Cartesian coordinates. Descartes was lying on his bed watching a fly. Slowly, it came to him that he could describe the fly’s position at any instant by just three numbers. Those three numbers were along the planes of the floor and two adjacent walls, what we now call the x,y,z coordinate system. Most cities today are laid out in Cartesian fashion, so we give directions as x,y coordinates easily and without realizing it.
When we tell a stranger to go three blocks down Main Street and then turn right on Jackson and go 10 blocks, we are using Cartesian coordinates. The Cartesian coordinate system is made up of two number lines, one usually labeled the x-axis which runs horizontally, the other usually labeled the y-axis which runs vertically. The axes meet where they both are zero, we call this point the origin. When working with equations (or inequalities) in two variables it is often useful to be able to show the values graphically, in which we use his system.
For centuries after algebra was invented mathematicians thought that equations like X^2 + 1 = 0 had no solutions. In the 16th C. an Italian mathematician called the solution to that equation the square root of -1 and then said this was just a symbol to represent a useless quantity. Around the same time, Rafael Bombelli invented operations for complex numbers. In the 17th C. Rune Descartes named the square root of -1 the imaginary number. Descartes made the important discovery of the Cartesian coordinate system, that is the basis of geometry and algebra. He was also made great philosophical contributions.