Apple is to tree as grape is to vine.
Hair = simile
apples = generalization
It refers to "Supreme Judge" when talking about intentions, and ends with firm reliance "divide providence." The Independent states now have power because they're separated from England.
Formal diction
Douglass's use of the words "severe trial" and "departure", as well as his sentence structure shows a more formal diction. He is basically saying nothing stopped him from leaving. However, he uses much more formal diction. Imagery is the creation of images in the reader's mind through description. There are no images in the reader's mind from this excerpt. There are also no elements of sentiment in the passage or subjectivity.