Premise: Merchants thronged to the large cities that were growing up around the castles at Edo (population already 1 million in the 18th century), Osaka (400,000), and Nagoya and Kanazawa (each 100,000) all huge in comparison with European cities of the time.

Hypothesis: Merchants thronged to the large cities, because they could sell their wares easily and for higher prices.
Relation: neutral