The seven-year-old Seymour in his letter reveals the strong influence on his beliefs of Indian religious mysticism, particularly the Vedanta branch of Hinduism. In this connection a functioning belief system becomes evident as the infant terrible matter-of-factly prophesies future events in his life and the lives of certain other Glass family members, especially Buddy. Foreknowledge and predestination, reincarnation (e.g., Seymour's allusions to his "appearances"), and revelation help shape the oracular, egocentric world view by which he lives. For all his very high-and-mighty manner, young Seymour acts as if he were under the spell of a very powerful being; an element of madness happens to accompany his tendency toward religious mysticism.
While his sexual awareness and responsiveness to female allure are given considerable attention in this story, much more is made of the child's literary interests and proclivities. He mentions his having written a considerable amount of poetry. But he mentions also five-year-old Buddy's having written six stories about an adventurous Englishman. Seymour speaks familiarly about great writers (for example William Blake and William Wordsworth) and certain academic scholars (possibly fictitious), and he requests that his parents obtain for him, from the Manhattan library, an enormous amount of serious reading matter. This includes the Victorian novelists, Tolstoi, Cervantes, Conan Doyle, Goethe, material about "the colorful and greedy Medicis" and "the touching Transcendentalists," as well as a selection of obscure periodicals of the mid-nineteenth century.
Hardly less important than the literary theme in Seymour's life is the idea and practice of prayer. Nondenominational Christianity is reflected to some degree in Seymour's treatment of the idea and practice of prayer, considered as separate from any specific religion. However, in line with his strong attachment to Eastern religious mysticism, he retains a fondness for Eastern forms of prayer. One of the other books he requests of his parents is "The Gayati Prayer, by unknown author."
Another thematic element, in connection with Seymour's childhood and his self-absorption, is that of death, which to him is simply a recurring phase of existence, like its opposite, the "appearance" on Earth once again. Though Seymour in his letter does not use the word "reincarnation" when speaking of his or Buddy's "appearances,” he clearly has in mind an ongoing sequential process of death and rebirth of the individual, whereby the grave has no victory and death has no sting. Hence Seymour's references to, or visions of, his coming death are neither sad nor fearful; rather, they tend in general to be accepting, somewhat like that of William Cullen Bryant in his famous vision-of-death poem "Thanatopsis" (1814). Before informing his parents that he will live thirty years or more, Seymour indicates that he has not always been good-humored about departing this Earth.