He is most keen on getting subjects, such as myself, for study over a very long period of time,--two to three years,--as he very justly observed “Muscular output is a very small part of the measure of a man’s efficiency. Mental efficiency, manual dexterity, and other psychological tests are necessary.” He seemed very much interested in my idea of making a large number of curves of daily observations. He said that it appeared to him to offer the best means of ultimately measuring the degree of deviation from the subject’s optimum state of health. He argues the necessity of getting some scientific definition of health. * * * * * The phrase that reduces all these people to contemplative silence is this. “You acknowledge that the state of knowledge is insufficient to prescribe a diet for any individual that he should take daily; or in other words, that there is very little accurate knowledge of the nutrition problem.” Reply. “Yes. I do not feel I could prescribe a diet for any one with any degree of confidence.” “Very well, then. Why should not the body have or acquire the quality that all animals have, in a free, natural state, of knowing what their body wants by appetite and taste?” This is more or less how you put it to me when I first met you at Cambridge. Its full significance did not dawn on me till much later; till, in short, I commenced the study of my desires at Cambridge. Now this point of view is the rock on which we stand, and is the cause of H.'s and A.'s interest, and as H. said, is the “most fascinating idea” he ever heard. It had very much the same effect on A. He was reduced to silence. The more you think of it the more you see there is no answer that could contradict it. _He then admits that_ (_a_) The food should be finely divided. (_b_) That it should be thoroughly insalivated. (_c_) That in all probability most diseases are caused by dietetic error. (_d_) That we have still to find the optimum health and the optimum diet. He only kicks at the low proteid. Now I don’t care a “kuss” for the low proteid, as such, or high proteid. Proteid like everything else will be demanded by the appetite when it is wanted. Our great danger, to my mind, is the tendency so strongly exemplified by some of prescribing diets and quantities and the length of time food should be chewed.[1] Now the very errors we are fighting against are the prescription of methods on insufficient information or knowledge. _You have gone straight back to Nature._ _There is your strength_ in convincing the scientific world, and we must study the problem from that point of view if we are to get any great degree of success.