Christiaan Huygens, a Dutch philosopher and mathematician, was one of the leading scientists in the 17h century. He started by trying to disprove theories that had been established by Ancient Greeks in geometry. He was interested in telescopes and astronomy, anc spent a lot of time designing methods to improve the mechanical and optic performance of telescopes. In his book entitled "Systema Saturnium' published in 1659, he noted the discovery of the rings around the planet Saturn, and made observations about the planets, the Moon, and Orion Nebula. His keen interest in the field of astronomy led him to measure time and other matters that relate to mechanical physics. One of his most important contributions was that he explained the vital principles of classical physics like centripetal force and gravity in a vacuum in another book of his. Huygens also put forward a theory explaining the wave behaviour of light. His reputation as a scientist and a scholar became known worldwide, and remains so to this day.
Born in the tenth century AD, Alhazen was an Arab who was known as the first true scientist. He developed the scientific method of experimentation, and was the first person to formulate hypothesis and conduct verifiable experiments. A scientist, philosopher, astronomer, and mathematician, Alhazen wrote over a hundred books, more than half of which have been preserved. One of his most influential writings was in the field of optics. In this book Alhazen gave experimental proof of the nature of light, the structure of the eye and the basic principles of reflection via mirror. He stated that contrary to popular belief, the eye does not send out rays to the object it sees. Rather it is the light reflected via the object that the eye beholds. This was a completely new and revolutionary concept. The book comprises sevenvoles, and was translated into Latin.
