In Sidereus Nuncius, Galileo revised and reproduced these two star groups by distinguishing between the stars seen without the telescope and those seen with it.[13] Also, when he observed some of the "nebulous" stars in the Ptolemaic star catalogue, he saw that rather than being cloudy, they were made of many small stars. From this he deduced that the nebulae and the Milky Way were "congeries of innumerable stars grouped together in clusters" too small and distant to be resolved into individual stars by the naked eye.[2]