[jfengel]

Tolkien's work shows influences of both the sagas and his own Catholicism. Often, they began with the North European influences and reconceived them in his own world-view. Most prominently, the story of Turin Turambar is inspired by the Finnish Kalevala, but became very different over decades of rewrites. Due to his son's lifetime of effort, we have an extraordinary wealth of information on the evolution of his work.

The universe containing Arda is very different from ours, but Tolkien used it to work out his philosophy of what humans mean in the universe. The Elves are bound to the world, but Men have the "gift of death" and get to go beyond it. The analogy to Heaven is too facile; what's really being explored is the problem of evil, suffering, and the fear of death. It's all an explicitly pre-Christian world, before the sacrifice of Christ and salvation, which allows him to dispense with the trappings of Christianity to look at the real nature of humans (as viewed through the eyes of a people who don't have that gift of death).

All of that is much, much more subtle than Lewis's simple allegories. (Tolkien famously wrote that he "cordially detested" allegories, though he indulged in them once in a while as well.) Reading Tolkien's influences deeply requires a Middle Ages mind-set, both medieval Catholic and pagan views.

None of that is necessary to enjoy, appreciate, and even study his books. But we have the luxury of being able to read the works as they developed, and that gives us an almost unique insight into the multiple worlds that influenced them.