Nowhere is the influence of Greece more obvious than in philosophy. Greek philosophers, including the Stoics, Panaetius (c. 185–109 B.C.), and Posidonius (c. 135–50 B.C.), visited Rome to lecture. Many spent extended periods there. In the first century B.C. it became the fashion for young upper-class Romans to study in Athens, in an ancient version of the eighteenth-century Grand Tour.