This section is from the book "The Home Hand-Book of Domestic Hygiene and Rational Medicine. Volume 2.", by J. H. Kellogg, M.D.. Also available from Amazon: The Home Hand-Book of Domestic Hygiene and Rational Medicine, Volume 2.
It is of great importance to recollect that the special directions for the diet in different forms of dyspepsia which we have given are not intended as rules to be followed for any great period of time. In many cases it is necessary to adhere strictly to the special dietary only for a few days, when the diet may by degrees be made to include a larger variety of foods. We would, however, impress upon the mind of the dyspeptic this fact; that when he finds himself well again, he must not make the error to suppose that the principle "once in grace always in grace" in any sense or in the smallest degree applies to the improved state of his digestion. Although the stomach may be restored to a sufficient degree of health and vigor to enable it to do its duty well under favorable circumstances, it will be certain to fail and relapse into a diseased state again as soon as those conditions are no longer supplied.