Mental and corporeal causes

Some physicians have laboured to prove that insanity is uniformly produced by a mental cause, or that it is in genral dependent on no bodily one; but their arguments are certainly inconclusive, and I am more disposed to subscribe to the converse proposition, that madness is always accompanied by corporeal disease, though this may not be obvious to the senses in every case.

C***
Practical Observations on Insanity, p. 81.