Note 837 — Chapter V · (continued 3)

Dr. Watson (Principles and Practice of Physic, 4th edit. London, 1857, vol. i. p. 41) says of the humoral pathology, that, ‘the absurdity of the hypothesis, and still more the dangerous practice which this doctrine generated, began to be manifest, and led to its total abandonment.’ But, with every respect for this eminent authority, I venture to observe, that this supposition of Dr. Watson's is contradicted by the whole history of the human mind. There is no well-attested case on record of any theory having been abandoned, because it produced dangerous results. As long as a theory is believed, men will ascribe its evil consequences to any cause except the right one. And a theory which is once established, will always be believed, until there is some change in knowledge which shakes its foundation. Every practical change may, by careful analysis, be shown to depend, in the first instance, on some change of speculative opinions. Even at the present day, many doctrines are generally held in the most civilized countries, which are producing dangerous practical consequences, and have produced those consequences for centuries. But the mischief which the doctrine engenders does not weaken the doctrine itself. Nothing can do that, but the general progress of knowledge, which, by altering former opinions, modifies future conduct.