Final answer:
Trephination is the ancient medical procedure where a hole was made in the skull to cure disease by allowing evil spirits to escape from the body.
Step-by-step explanation:
The ancient procedure believed to let evil spirits escape from the body, thus curing disease, is known as trephination. This practice involved making a hole in the skull, which our ancestors across various cultures thought would release harmful spirits responsible for mental illness and other disorders. While modern medicine has vastly different approaches to treating diseases, understanding historical practices like trephination provides valuable insight into the development of medical knowledge and cultural beliefs regarding health and disease.