Ritualistic/sacrificial connection to nature vs. Christianity
Upon arriving to this new and fertile land Joseph gets a strange sense of connection to it vividly described when he makes the land his wife for a moment. When he gets the news of his father's death he doesn't feel sad because suddenly he gets a realization that his father entered the nearby old oak tree. That tree becomes the centre of the land and centre of Joseph's worship and peace. He unconsciously starts making sacrificial offerings to it in hopes of keeping the order in the land. Another act of ritualistic offering is the villagers' dance that turns delirious making it look like devil's worship in the eyes of the religious Burton. Following the death of the oak tree dry years come to the land. Whether this is coincidental or not it is left up for discussion.
For Joseph, the death of the tree meant the death of the land and the key importance of that tree was true to him. This ritualistic behavior is something neither Joseph nor the old man at the sea cliff can explain the reason to. They do it because it feels in their nature the right thing to do. At the end of the novel Father Angelo's reluctance to intervene with the villagers' ritualistic dance for the rain strengthens the importance of the act. The reason why the rain came at the end is left vague. On one hand we have Joseph making the last and definite sacrifice to the land, on the other we have Father Angelo praying for the rain. Both of them believed in their own way that their actions had impact on the coming of rain and both are true to them.
The finality of death
Death is not an uncommon aspect of the novel. At the beginning when his father died, Joseph didn't feel his death because he saw that his father was with him now in the tree, but when the old oak tree died Joseph felt the finality of his father's death and the support that he had was gone. After Elizabeth suddenly died, Joseph contemplated the finality of her death describing how all the opinions, all the thoughts, life was gone in a single moment. The only evidence of her life was the sound of the clock she previously wound up and the dampness of the socks that she hung.
