I recommend Josef Suk, a student of Dvorak, and his "Asrael" symphony. I remember somebody here made me discover Frederick Delius and his "Mass of Life" inspired by the works of Nietzsche. I suggest you listen to that too if you do not know the piece. To my knowledge, he is generally overlooked. Delius incorporated elements of Afro-American music in his work before Gershwin did.