What is the significance of uphill in the novel?

The only significant place I recall uphill is the ending of the novel. Jonas and Gabriel are trudging up a snowy hill with their sled. At the top they huddle together to slide down. They slide down into something, but we don't really find out what until the next novel. So, uphill could symbolize the search for truth. Also the search for relief and wisdom they seek far away from the world that they lived in (largely based on illusion).