Frankenstein is written in the mode of the epistolary novel, a form popularized in the eighteenth century by Samuel Richardson in his novels Pamela (1741) and Clarissa (1748) and expanded across class and social demarcations by Tobias Smollett in The Expedition of Humphrey Clinker. By the nineteenth century the epistolary form was something of an antique, its dynamics having largely been subsumed by other first-person narrative modes that allowed their authors greater flexibility. Mary Shelley's novel, which overtly advertises its modernity in a subtitle, is curiously, then, the last major example of the form in English fiction. The epistolary mode inherently stresses communication and process, major thematic concerns of the novel, and it accentuates a reliance on a variety of self-conscious narrators who are not easily subject to interrogation by one another nor the reader. Mary Shelley's stress on individual perspective and on its resulting narrative indeterminacy are conspicuous features of her novel.
It is interesting to contemplate the fact that a principal account of William Parry's Arctic expedition of 1819, Letters Written during the Late Voyage of Discovery in the Western Arctic Sea (1821), is also couched in an epistolary form. This might indicate some of the same thematic associations, structurally speaking, that the form held for Mary Shelley, or, more immediately, it could reveal her sudden and striking influence on subsequent travel narratives into inaccessible reaches of the globe.