Final answer:
The author of the lines is Paul Laurence Dunbar. He was an American poet and novelist known for his use of African American dialect and his exploration of racial identity and the experiences of African Americans.
Step-by-step explanation:
The author of the lines 'In time, although the sun is setting on A song-lit race of slaves, it has not set; Though late, O soil, it is not too late yet To catch thy plaintive soul, leaving, soon gone, Leaving, to catch thy plaintive soul soon gone' is Paul Laurence Dunbar. Dunbar was an American poet and novelist, known for his use of African American dialect in his works. He often addressed themes of racial identity and the experiences of African Americans. These lines are from his poem 'The Haunted Oak,' which explores the legacy of slavery and the possibility of redemption.