The burning question underpinning the story is this: What is the nature of reality?
This metaphysical enigma is first mentioned in chapter one when William says he came upon a damaged oak in the Botanic Gardens and his “mind was set to wonderin’ about that Idealist limerick” about God and the tree. The term idealism has multiple meanings. Here it is used in its philosophical sense, for I refer to the Irish bishop George Berkley’s radical position on the nature of reality, also known as immaterialism, it being the polar opposite of materialism, by means of which the good bishop sought to prove the existence of a supreme being who sees and sustains the universe. It is tantamount to the telling of the tale that immaterialism can be seen as a viable explanation of the nature of reality.
Although Will is curious about his own intuitive experience of the holy, by no means is he preoccupied with unveiling the nature of our universe. Will is confused, depressed, and subject to the many weaknesses of the flesh. He is also a realist in the Aristotelian sense of the term, and that is why he struggles to make sense of a mystical experience that makes little sense. Father Peadair, however,believes the conventional conception of reality is fundamentally flawed. He is an extreme Idealist whose duty is to enlighten Will to the true metaphysics of God’s creation. The source of the father’s authority becomes incrementally evident as the tale unfolds.