He reached in his pocket, and a piece of metal, slung on a ribbon, fell into my palm.
Too much evidence?
Gatsby carries “proof” (the medal) in his pockets of his past.
He thinks that it will give him more credibility, but if Gatsby had actually done all of the things he claims, he would not feel so insecure and paranoid that people would not believe him. This constant performance of his goes back to the unbroken series of successful gestures Nick mentions in Chapter One. Gatsby seems to have prepared answers and evidence for every aspect of his life. He doesn’t realize that acting casual is more convincing.
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