How would you explain ‘reveals letter’ in the context?
The New York Times, April 15, 1939
Rivera Still Admires Trotsky; Regrets Their Views Clashed
Artist Explains He Quit Fourth International So as Not to Embarrass Leader—Reveals Letter Caused Their Rift
By Diego Rivera
MEXICO CITY, April 14—The incident between Trotsky and myself is not a quarrel. It is a lamentable misunderstanding which, going too far, brought about the irreparable. That compelled me to break my relations with a great man for whom I always had, and I continue having, the greatest admiration and respect. I am very far from harboring the silly presumption of engaging in a polemic with Trotsky, whom I consider the center and the visible head of the revolutionary movement that is the Fourth International.
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How would you explain ‘reveals letter’ in the sentence: Artist Explains He Quit Fourth International So as Not to Embarrass Leader—Reveals Letter Caused Their Rift?
PS: It’s the title of a report on The New York Times.
Thanks!