Original sentence: Historically, chiropractic strongly opposed vaccination based on the belief that all diseases were traceable to causes in the spine, and therefore could not be affected by vaccines; DD Palmer once  wrote, "It is the very height of absurdity to strive to 'protect' any person from smallpox or any other malady by inoculating them with a filthy animal poison
Edited sentence: Historically, chiropractic strongly opposed vaccination on the grounds that diseases are traceable to causes in the spine, and therefore cannot be affected by vaccines; DD Palmer once  wrote, "It is the very height of absurdity to strive to 'protect' any person from smallpox or any other malady by inoculating them with a filthy animal poison