Rav Shach on Chol Hamoed

Over the years Rav Brevda used to go to Rav Shach to speak over Divrei Torah and hashkofoh. One time Rav Shach visited Rav Brevda on Chol Hamoed, when Rav Brevda was not feeling well, and heard from him an explanation of something the Gra said. Rav Shach was overjoyed at the explanation, and he told his talmidim, "Whoever has not heard an explanation like that one does not know what Simchas Yom Tov is."