to a mixed diet, if he had
imbibed no doubts in regard to a diet exclusively vegetable; and, above
all, how happened he to recover on it? To this it may be replied, that
there is every reason to believe, from the tenor of the letter, that he
acted against his own inclination, and contrary to his own views, at the
request of his friends, and of Dr. Harden, his physician; though Dr.
Harden does not expressly say so. Besides, it does not appear that under
his mixed diet there was any favorable change, till something like six
months had elapsed. This was a period, in all probability, just
sufficient to allow the poison of the gases to disappear; after which
he might have been expected to recover on any diet not positively bad.
If this is not a true solution of the case, how happens it that there
was no disease of any organ or function, except the nervous function?
There is every reason for believing that Dr. Harden, at the date of his
letter, had undergone a change of opinion, and was himself beginning to
doubt whether the regimen had any agency in producing the debility.[3]

The case of Dr. Preston is somewhat more difficult. At first view, it
seems to sustain the old notion of medical men, that, with a scrofulous
habit, a diet exclusively vegetable cannot be made to agree. This, I
say, seems to be a natural conclusion, _at first view_. But, on looking
a little farther, we may find some facts that justify a different
opinion.

Dr. Preston was evidently timid and fearful--foreboding ill--during the
whole progress of his experiment. We think his story fully justifies
this conclusion. In such circumstances, what could have been expected?
There is no course of regimen in the world which will succeed happily in
a state of mind like this.

It should be carefully observed by the reader, that Dr. Preston speaks
of entering upon a "severe course of diet;" and also, that, in
attempting to give an opinion as to the best kind of vegetable food, he
speaks of potatoes, prepared in a certain specified manner, as being
preferable to any other. Now, I think it obvious, that Dr. Preston's
"severe course" partook largely of _crude_ vegetables, instead of the
richer and better farinaceous articles--as the various sorts of bread,
rice, pulse, etc.--and, if so, it is not to be wondered at that it was
so unsuccessful. In short, I do not think he made any thing like a fair
experiment in vegetable diet. His testimony, therefore, though
interes