Dickinson as a mystic poet

Emily Dickinson is obviously a mystic poet. The themes that a mystic poet deals with are those of God, soul immortality, union of the human soul with the Divine. Emily Dickinson deals with all those themes in a good number of her poems. Her position as a mystic poet is based on her treatment of the themes relating to those metaphysical entities. But before we discuss the nature of her mysticism, we should have some terms of reference to determine the degree of her mysticism. Or, in other world, we should define mysticism, and in the light of that definition, we should discuss Dickinson as a mystic poet. 
Mysticism means spiritual quest for union with the Divine. But Mysticism has been practiced in different forms in different religions. In Hinduism, it means absorption of the soul in the All. Buddism emphasises meditation as a means of moving toward Nirvana. She wrote poetry of great power questioning the nature of death and immortality.