Debate concerning human enhancement often revolves around the question of whether there is a common “nature” that all human beings share and which is unwarrantedly violated by enhancing one’s capabilities beyond the “species-typical” norm. I explicate Thomas Aquinas’s influential theory of human nature, noting certain key traits commonly shared among human beings that define each as a “person” who possesses inviolable moral status. Understanding the specific qualities that define the nature of human persons, which includes self-conscious awareness, capacity for intellective (...) thought, and volitional autonomy, informs the ethical assessment of various forms of enhancement. Some forms of cognitive and physical enhancement may be desirable from the perspective of what constitutes the “flourishing” of human persons in our fundamental nature; while other forms of enhancement, such as emotive or so-called “moral” enhancement, run the risk of detracting from human flourishing when evaluated from the virtue-theoretic perspective Aquinas promotes. (shrink)