Sidereus Nuncius is Galileo's work in which he shares his observations made with the telescope recently invented in Holland. It was only with this new device that he was able to observe the rough surface of the Moon, the multitude of stars in Orion, the Pleiades, the Milky Way, the resolution of star nebulae into many individual stars, and the moons of Jupiter. These discoveries supported the Copernican system and abolished the essential difference between the sublunar and supralunar worlds. In the introductory essay by Hans Blumenberg, the special role of the telescope in the interplay between science and technology is highlighted. For Galileo, the use of technical devices no longer means acting against nature, but rather in harmony with it. Therefore, technical means legitimately participate in the laws of nature.