However, the fitness of various Foods, and Drinks--and the quantity of Nutriment which they afford--depends very much upon how they are prepared, and as much on the inclination and abilities of the concoctive faculties, which have the task of converting them into Chyle. It is quite as absurd, to suppose, that one kind of Diet, &c. is equally adapted to every kind of Constitution--as that one Remedy will cure all Diseases. _To produce the highest degree of Health and Strength_--we must supply the Stomach with not merely that material which contains the greatest quantity of Nourishment--but in making our reckoning, must take into the account, the degree in which it is adapted to the habits and powers of the Organ which is to digest it--the Arms of a Giant are of little use in the Hands of a Dwarf. _The Plan we have proposed, was calculated for Midsummer-day_,--when plenty of hard Exercise in the open Air will soon create an Appetite for the substantial Diet we have recommended--it is taken for granted, that a Person has the opportunity of devoting a couple of months to the re-establishment of his Health--and that during that time, he will be content to consider himself in the same state as any other Animal out of condition--and disposed to submit cheerfully to such a modification of the rules recommended, as his Medical Adviser may deem most convenient to the circumstances of the Case, and the Age, the Constitution, and previous habits of the Patient, &c. &c. _Every part of this system must be observed in proportion_--and EXERCISE increased in the same degree, that NOURISHMENT is introduced to the Constitution. _The best General Rule for Diet_ that I can write, is to Eat and Drink only of such Foods--at such times,--and in such quantities--as Experience has convinced you, agree with your Constitution--and absolutely to avoid all other. A very different Regimen must be observed by those who live a Life with Labour--or Exercise--or of Indolence,--and at the different Periods of Life. HUMAN LIFE may be divided into _Three Stages_. The FIRST, _The period of Preparation_ from our birth, till about our 21st year, when the Body has generally attained the _acmé_ of expansion:--till then, a continual and copious supply of Chyle is necessary, not only to keep our machinery in repair, but to furnish material for the increase of it. The SECOND from 21 to 42, _The period of Active Usefulness_; during which, nothing more is wanted, than to restore the daily waste, occasioned by the actions of the Vital and Animal Functions. The THIRD, _The period of Decline_: this comes on and proceeds with more or less celerity, according to the original strength of the Constitution, and the Economy[16] with which it has been managed during the second period. (Age is a relative term,--one man is as old at 40 as another is at 60): but after 42, the most vigorous become gradually more passive[17]--and after 63, pretty nearly quite so.