What is marco polo thesis and hes tragedy and hes triumph

Marco Polo (1254-1324) was a Venetian merchant believed to have journeyed across Asia at the height of the Mongol Empire. He first set out at age 17 with his father and uncle, traveling overland along what later became known as the Silk Road. Upon reaching China, Marco Polo entered the court of powerful Mongol ruler Kublai Khan, who dispatched him on trips to help administer the realm. Marco Polo remained abroad for 24 years. Though not the first European to explore China—his father and uncle, among others, had already been there—he became famous for his travels thanks to a popular book he co-authored while languishing in a Genoese prison.

It's probably because some types of violets are blue