Personality is an unbroken series of successful gestures.
At the very beginning of the novel the author uses this phrase to describe the main character - Jay Gatsby. We see him as the heroic and romantic character, a self-made man who now doesn’t allow himself to fail in any, even insignificant thing. This quote is also a foreshadowing of the future story and the past of the character.
His personality developed from the poor military officer who didn’t have anything except his ideals to the refined man from the upper crust of the society. He mercilessly forced himself to study every day to achieve his goal, for years. He tried anything, sacrificing some of his ideals to get the woman he loves - but he never becomes someone like Tom. He is cunning, sometimes ruthless and extremely determined, but still he is capable of love, generosity and kindness. The tragic ending of the story is the consequence of his “series of successful gestures” finally broken. We see that this makes his personality and his very will to live break also.
He doesn’t care when Wilson comes to kill him, he feels like he has already transitioned to the afterlife: the world is devoid of color, taste and sound. The personality and the soul of Jay Gatsby are already dead, and the body is waiting to join them. The ideals of Gatsby play against him at the end: he was so determined, that, when his goal became impossible to achieve and the woman he loved ultimately refused to elope with him, Gatsby couldn’t accept any other goal. His loss is the loss of the knight and his death looks like one described in legends. His personality was indeed made by the line of successes and was completely destroyed by the single ultimate failure.