Adam Clarke on Daniel 4:16

Let his heart be changed - Let him conceive himself to be a beast, and act as such, herding among the beasts of the field.

Let seven times pass over him - Let him continue in this state for seven years. I knew a man who was thus changed in his heart - in his imagination. He believed himself to be a bear, and would imitate the ursal growl, etc.; and the case did not appear to be hypochondriacal. Whether he ever came to sound mind, I know not.