So remember this: Wall Street did not emerge fully formed—and fully detestable—as some unknown villain’s grand plan to empower the rich at the expense of the poor. Wall Street evolved over some four hundred years from the simple idea that people have different skills and different talents allowing them to produce different goods and services and that, one way or another, those goods and services need to be sold by the people who made them and bought by the people who want them. Period.
-- William D. Cohan (chapter 1 paragraph 2)

Importance: This demonstrates Cohan's argument that Wall Street is an organic institution, created out of collective need. He argues that vilifying Wall Street implicitly assumes it was created with the malicious intent of generating wealth for bankers.

Where we collectively lost our way with Wall Street was when the personal risk involved in financial bets became decoupled from the rewards for them by allowing...
-- William D. Cohan (chapter 2 paragraph 3)