Column of Dust by Evelyn Underhill

Evelyn Underhill, the preeminent scholar of mysticism, wrote 3 novels in her youth, of which this is #3. Constance Tyrrel, a poor but literate woman works in a bookshop, suffers ennui, wonders if there is more to life than what she sees, invokes a ritual that she finds in a dusty old volume. Meanwhile, a disembodied spirit is consumed by a desire to know about the nature and content of the material world. It is drawn by Constance's call, where it appears as a column of dust. The two embark on adventures edifying to both and, incidentally to the reader. - Summary by Josh Mitteldorf