NIggle's Artwork
Niggle is a painter, and he represents the artistic dreamer. Naturally, Tolkien includes a significant amount of imagery relating to artwork in this story. Niggle's artwork, while not described in great detail, still uses artistic phrasing. For example, it is said that when painting a leaf, Niggle works obsessively, "trying to catch its shape, and its sheen, and the glistening of dewdrops on its edges" (1). The whole of his Great Tree is described with tranquil and specific imagery, suggesting its importance in the Afterlife.
The Hospital
When Niggle is sent to the Workhouse (essentially Purgatory) by the Porter, he has an impression that is some sort of hospital. While he is there, he is forced to take bitter medicine, and he must interact with stern-faced nurses and doctors, further examples of this sterile hospital imagery. This imagery is important for understanding the nature of the Workhouse; while it is unpleasant for Niggle, it is shaping him and purging his imperfections, simulating a hospital by making him well and curing him of his sickness.
Death
While death is never referred to as such in this story, it is heavily implied by the "journey" Niggle undertakes. Tolkien uses imagery to bring this implication about, and such imagery is notably gentle and accommodating. For example, when it is Niggle's time to go, the Driver shows up at his door, a tall, imposing man dressed entirely in black who immediately takes him to the train station. His appearance is to be expected, but he is rather a pleasant man, far from the cruel portrayal of death as the Grim Reaper in popular culture.
Niggle's Country
"Leaf by Niggle" is essentially concerned with the use and role of the imagination in human life. Tolkien is an avid fan of the imagination, dedicating essays to its application and value, and his appreciation is evident in this story, especially after Niggle goes on his journey. After Niggle's stay at the Workhouse, he enters a beautiful land called "Niggle's Country," a land that seems to function on art and imagination. This is related through imaginative imagery, including descriptions of the place that seem to defy natural laws and heighten the sense of the imagination. When Niggle finally enters the Mountains at the story's end, this sense of imagination reaches its fullest conclusion.
