Nick believed that Gatsby modeled himself on an idealized version of who Jay Gatsby really was.
Explanation:
Based on the Plato's teaching within the question it can be said that it seems that Nick believed that Gatsby modeled himself on an idealized version of who Jay Gatsby really was. Such as is his imperfect reflection of the idealized version that Gatsby has created in his mind, similar to what Plato stated to be the case with many reality itself.
A river gives the inhabitants a reliable source of water for drinking and agriculture. Additional benefits include fishing, fertile soil due to annual flooding, and ease of transportation. The first great civilizations, such as those in Mesopotamia and Ancient Egypt, all grew up in river valleys.