As the Greek verbal system has become the subject of various dissertations and monographs, the future tense-form has been generally overlooked in the discussion. This dissertation seeks to overcome this lacuna by suggesting that the future tense-form functions as a rhetorical feature that expresses the author's expectation of an alternative state of affairs so that the hearer adjusts his or her thoughts, behaviors, or emotions in light of this expectation. This definition is developed through three major steps. First, following a survey of the various construals of the future tense-form by both ancient and modern grammarians, a corpus-driven discourse analysis from a systemic-functional perspective is proposed. As a corpus-driven approach this methodology seeks to develop the definition of the discourse function of the future tense-form directly from its usage in the corpus. As a systemic-functional approach, the methodology recognizes the role of language to portray one's understanding of reality as a tool to affect other people. Second, through analysis of each occurrence of the future tense-form in the corpus is categorized according to a functional taxonomy that recognizes the author's apparent purpose and that acknowledges generic differences in the formation of a text. This analysis suggests an appeal to an unrealized state of affairs. This description is developed through the application of probabilistic grammar to the various categories of the taxonomy. Third, since Greek authors can utilize the future tense-form or various other constructions when referring to future-time, several other constructions--including verbs that indicate future inception through their semantic features, deictic markers, the aorist tense-form in the apodosis of future time-referring conditions, periphrastic constructions, and complementary infinitives with do?e[varpi]--are examined following the same methodology. Analysis of these results according to probabilistic grammar suggests that the future tense-form further is a rhetorical expression of the author's expectation of this unrealized state of affairs in order to affect the reader's thoughts, behaviors, or emotions. As a result, this dissertation contributes not only a possible definition of the discourse function of the future tense-form, but also an analysis of the proleptic aorist that contributes to greater clarity in its characterization and a confirmation of the usefulness of one proposed corpus for the study of Hellenistic Greek. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]