Ed Sheeran performed part of his song “Thinking Out Loud” in a New York courtroom Thursday as he tried to explain to jurors how he came to write the hit that landed him in legal trouble. The heirs of Ed Townsend, the man who co-wrote Marvin Gaye’s 1973 classic “Let’s Get It On,” filed the copyright lawsuit accusing Sheeran of plagiarizing elements of Gaye’s tune. After about an hour of giving testimony in Manhattan federal court Thursday, Sheeran grabbed a guitar and sang parts of his song, bringing “smiles to the faces of some of the spectators in the courtroom,” according to the Associated Press. Sheeran also made claims about being able to write music with astonishing speed, sometimes writing nine songs in a single day and adding that he had written 10 songs last weekend alone.