Galileo calls his compound microscope with a concave and a convex lens the occhiolino, or little eye. The magnifying device is a gateway drug—he soon starts experimenting with telescopes ...

Then, a maker paired convex and concave lenses together, in an approach similar to how telescopes were made, creating the first compound microscope. By 1625, ...

The properties of concave and convex lenses were first described around the year 1000, ... His refined compound microscope, described and illustrated in the preface to his book, ...