Greg Smith is a Goldman Sachs “executive director” and “head of equity derivatives” in Europe, the Middle East and Africa. And, as you may have heard, today is his last day at the firm. Greg had a speech prepared for the big announcement, which he stayed up all night writing and planned to deliver on the trading floor at noon, but assuming security has other ideas, we volunteered to relay his story. A word of advice: brace yourselves.

Why is Greg resigning from Goldman Sachs? To understand why he’s leaving, you have to know what it was like when he got here, twelve years ago.

It might sound surprising to a skeptical public, but culture was always a vital part of Goldman Sachs’s success. It revolved around teamwork, integrity, a spirit of humility, and always doing right by our clients. The culture was the secret sauce that made this place great and allowed us to earn our clients’ trust for 143 years. It wasn’t just about making money; this alone will not sustain a firm for so long. It had something to do with pride and belief in the organization.

For a while, Greg loved Goldman Sachs! And the feeling was mutual, otherwise they obviously would not have bestowed him the great honor of being “selected as one of 10 people (out of a firm of more than 30,000) to appear on the recruiting video, which is played on every college campus we visit around the world.” Shortly after the cameras rolled and he got his star turn, though, things began to change. And not in a good way. Greg suddenly noticed that the culture that made him “love working for this firm” was gone. He no longer had “the pride, or the belief.” The moment of truth? When he realized he “could no longer look students in the eye and tell them what a great place this was to work.” It didn’t matter how great a performance he gave in those videos. It didn’t matter that audiences would ask if he really worked for Goldman or if they’d hired an actor, as he appeared to have been classically trained. It didn’t matter that his recruiting DVD had been nominated for several trade awards. It didn’t matter because Greg had seen too much.

Read more on Dealbreaker.