Complex sentence: In 1915, Lukács returned to Budapest, where he was the leader of the Sunday Circle, an intellectual salon whose concerns were the cultural themes that arose from the existential works of Dostoyevsky, which thematically aligned with Lukács's interests in his last years at Heidelberg.
Split into simpler sentences: In 1915, Lukács returned to Budapest, where he was the leader of the Sunday Circle, an intellectual salon. Its concerns were the cultural themes that arose from the existential works of Dostoyevsky, which thematically aligned with Lukács interests in his last years at Heidelberg.