Answer:
Shelley is trying to say that our modern culture, Western culture, owes many things to the invaluable heritage of Greece. The ancient culture of Greece is the craddle of European, Western civilization.
Its great philosophers laid the foundations of current Western philosophical views and concepts; Greek theater left us imperishable dramas and comedies that are still part of our culture; Greek mythology inspired arts and literature for many centuries; our greatest modern sports event, the Olympics, are named after a famous Greek competition. Greek , together with Latin, provided European languages with many words that are still in use in the sciences and in everyday life. Of course, we are all Greek.
Explanation: