Final answer:
Florence Nightingale is recognized as the first nurse theorist and her theories had a significant impact on the nursing profession.
Step-by-step explanation:
The first nurse theorist is Florence Nightingale. Nightingale is widely considered the foundational philosopher of modern nursing and her theories shaped the profession. She emphasized the importance of providing a clean and healing environment for patients and established the foundation of modern nursing education. Nightingale's contributions to nursing theory continue to be influential today.