Rene Descartes (1596-1650)
a french thinker, wrote a book called "discourse on the Method of Rightly Conducting the Reason and Seeking for Truth in the Sciences" (1637). Descartes felt that to understand the universe a person had to start with what was certain and mathematically deduce how the universe works. He started with the statement "Cogito Ergo Sum" ( i think, therefore I am). Descartes felt the universe existed at God's will but that the mathematical order of nature was the same as God. This approach was called the Cartesian method and it was one of the most important advances in exploring scientific questions.