Thomas Kyd's The Spanish Tragedy creates a subtle apologia for the “middling sort” by challenging the socially constructed predicates of aristocratic privilege. A scrivener's son, Kyd undertsood oeconomia, or household management, as both the means for material advancement among the “middling sort” and a potential threat to aristocratic insularity. His translation of Torquato Tasso's The Householder's Philosophy, a work rarely studied by literary scholars, reveals an abiding interest in the political import of natural philosophy on class structure. More particularly, through his sophisticated revision of Aristotelian faculty psychology, Kyd appropriates early modern understandings of the vegetative soul—the source of all reproduction, nutrition, and growth inherent in all living things —to reveal middling ambition as a natural phenomenon. By representing the latent desire for growth and development as the consequence of an innate psychology, Kyd's play transforms revenge into an understandable outgrowth of thwarted ambition, a type of reproduction by absense, when all lawful means of material advancement become foreclosed. Rather than simply irrational and brutish, or, conversely, highly calculative, revenge appears throughout Kyd's play as instinctively reproductive as well.