In this article the author confirms a well known Aristotle's statement on Thales being the first philosopher. By carefully analyzing the Metaphysics, On the Heavens and On the Soul, one can find relevant paragraphs which support the Stagirite's remark about a wise man of Miletus as the founder of something which would later become known as the "Greek wonder". When interpreting here quoted Aristotle's statements there are three key points: 1.) The Earth rests on the water (Met.983b21-22; Cael.294a28), 2.) Water is the material cause of all things (in Met.983b19-21 the water is mentioned as the arche, and before that in Met.983b7 it is said that for the majority of the first philosophers the principles which were of the nature of matter were the only principles of all things), and 3.) All things are full of gods (De an.411a7-8; it is also added that the magnet is alive; for it has the power of moving iron, De an.405a19-21). After reconstruction of Stagirite's writings on Thales it was determined that his significance for philosophy lies in the fact that he, having considered the whole variety of known world, detected a unique principle which lies, or, even better, underlies beneath self-evident and obvious variety. In fact, when Milesian proclaimed the water as the first principle of all things, he tried, in a "natural" and scientific manner, without myths and supernatural forces, to explain the whole of cosmos. Thus, he gained the reputation of "the founder of philosophy".