May be, it is compass.
the alphabet
The Greeks invented theaters, or amphitheaters, not only to improve sound quality of a show being put on, but also to improve the effectiveness of how much people can see. The Greeks invented rows, or seats, going back and higher to make it easier for people to see.
the greeks
because they were good cool
Many Greeks became sailors and traded with other people.
The Greeks did
Greeks invented many weapons. One such weapon was the ballista which was used by the Greeks as a siege weapon in war.
Poseidon, ruler of the seas.
They need to so they can transport others :)
No they did not
It was invented by the Greeks
Many ancient Greeks became traders because unless you were rich or a slave there was no other job opportunity and sailors because their lives were dependent and surrounded by the sea and so this was an expected career for them.