Loss and grief can have powerful effects on the mind. The supernatural is proof that death is not the end. Fear is only a state of mind, and cannot significantly harm anyone.
It tells of a talking raven's visit to a distraught lover, who is grieving over the loss of his beloved, Lenore, and falling into madness. This poem can be called a poetical study of grief. ... Based on this, we can see that the central theme of the text is that loss and grief can have powerful effects on the mind.
Part a is: Loss and grief can have powerful effects on the mind.
Part b is: “Eagerly I wished the morrow; — vainly I had sought to borrow / From my books surcease of sorrow — sorrow for the lost Lenore — ” ( Lines 9-10)