Shakespeare was writing in the time scientific time of taxonomy, where things are compared to one another to create their own classification. So this declaration from Kent to Oswald would be typical of an Earl's education. This could have given away his disguise, as he was dressed as Caius in A1 S4, and a peasant wouldn't have been as educated.
Let me start by saying there is no way I can do this man justice in just one little blog post. What I can say, simply, is that any kind of development in astrology, astrophysics, astronomy, or astrobiology in the past 50 or so years would have some connection to Carl Sagan.