Time
This novel focuses much of its prose and plot around the issue of time. On the one hand, time is inevitable. In Mercy's case, it is also fatal and tragic, bringing all her family 25 years closer to death before she gets a chance to visit and see them. Time is offered as the stake of human life. Who wouldn't do anything for more time? And yet, there is also the consideration of quality of life, and she has to weigh the opportunity to be with her family with the short nature of human life.
Home and family duty
Although the family loves Mercy, there are obviously mixed feelings about her having left the family. That isn't exactly her fault though, because of the details of that, and because after all, she was married to the same man for 25 years in Scotland. It isn't like she was off doing nothing. But, the picture of family duty that Jake demonstrates is clearly less individualistic in nature, so family duty is a crisis in her life.
Thought and academy
Many of the opportunities in Mercia's life are those that came from her passion for rigorous contemplation and thought. She often goes into lengthy passages of prose, and the latter half of the novel is thought-driven, not plot-driven. Again, she is a professor in Glasgow before she comes home, so the reader can know automatically that she is a professional thinker, so to speak. She scrutinizes life in Africa and Europe before making a decision.
