Final answer:
Dorothea Orem is the nursing theorist who encouraged the use of one's own powers through her Self-Care Deficit Theory, which promotes patient autonomy and self-care.
Step-by-step explanation:
The nursing theorist who encouraged the use of one's own powers was Dorothea Orem. Dorothea Orem developed the Self-Care Deficit Theory, which is predicated on the belief that individuals can be responsible for their own health and the care they require. In her theory, Orem emphasizes the importance of self-care and the role of the nurse in supporting and teaching patients to perform self-care activities. Orem's theory underscores the significance of patients' autonomy and their capacity to engage in self-care practices, thereby empowering them to take control of their own health. The aim is for individuals to maintain as much independence as possible by using their own powers to meet their own care needs.