O thou who art attracted to the fragrant breathings of God! I have read thy letter addressed to Mrs. Lua Getsinger. Thou hast indeed examined with great care the reasons for the incursion of disease into the human body. It is certainly the case that sins are a potent cause of physical ailments. If humankind were free from the defilements of sin and waywardness, and lived according to a natural, inborn equilibrium, without following wherever their passions led, it is undeniable that diseases would no longer take the ascendant, nor diversify with such intensity.

But man hath perversely continued to serve his lustful appetites, and he would not content himself with simple foods. Rather, he prepared for himself food that was compounded of many ingredients, of substances differing one from the other. With this, and with the perpetrating of vile and ignoble acts, his attention was engrossed, and he abandoned the temperance and moderation of a natural way of life. The result was the engendering of diseases both violent and diverse.

For the animal, as to its body, is made up of the same constituent elements as man. Since, however, the animal contenteth itself with simple foods and striveth not to indulge its importunate urges to any great degree, and committeth no sins, its ailments relative to man's are few. We see clearly, therefore, how powerful are sin and contumacy as pathogenic factors. And once engendered these diseases become compounded, multiply, and are transmitted to others. Such are the spiritual, inner causes of sickness.

The outer, physical causal factor in disease, however, is a disturbance in the balance, the proportionate equilibrium of all those elements of which the human body is composed. To illustrate: the body of man is a compound of many constituent substances, each component being present in a prescribed amount, contributing to the essential equilibrium of the whole. So long as these constituents remain in their due proportion, according to the natural balance of the whole-- that is, no component suffereth a change in its natural proportionate degree and balance, no component being either augmented or decreased--there will be no physical cause for the incursion of disease.

For example, the starch component must be present to a given amount, and the sugar to a given amount. So long as each remaineth in its natural proportion to the whole, there will be no cause for the onset of disease. When, however, these constituents vary as to their natural and due amounts --that is, when they are augmented or diminished--it is certain that this will provide for the inroads of disease.

This question requireth the most careful investigation. The Báb hath said that the people of Bahá must develop the science of medicine to such a high degree that they will heal illnesses by means of foods. The basic reason for this is that if, in some component substance of the human body, an imbalance should occur, altering its correct, relative proportion to the whole, this fact will inevitably result in the onset of disease. If, for example, the starch component should be unduly augmented, or the sugar component decreased, an illness will take control. It is the function of a skilled physician to determine which constituent of his patient's body hath suffered diminution, which hath been augmented. Once he hath discovered this, he must prescribe a food containing the diminished element in considerable amounts, to re-establish the body's essential equilibrium. The patient, once his constitution is again in balance, will be rid of his disease.

The proof of this is that while other animals have never studied medical science, nor carried on researches into diseases or medicines, treatments or cures--even so, when one of them falleth a prey to sickness, nature leadeth it, in fields or desert places, to the very plant which, once eaten, will rid the animal of its disease. The explanation is that if, as an example, the sugar component in the animal's body hath decreased, according to a natural law the animal hankereth after a herb that is rich in sugar. Then, by a natural urge, which is the appetite, among a thousand different varieties of plants across the field, the animal will discover and consume that herb which containeth a sugar component in large amounts. Thus the essential balance of the substances composing its body is re-established, and the animal is rid of its disease.

This question requireth the most careful investigation. When highly-skilled physicians shall fully examine this matter, thoroughly and perseveringly, it will be clearly seen that the incursion of disease is due to a disturbance in the relative amounts of the body's component substances, and that treatment consisteth in adjusting these relative amounts, and that this can be apprehended and made possible by means of foods.

It is certain that in this wonderful new age the development of medical science will lead to the doctors' healing their patients with foods. For the sense of sight, the sense of hearing, of taste, of smell, of touch--all these are discriminative faculties, their purpose being to separate the beneficial from whatever causeth harm. Now, is it possible that man's sense of smell, the sense that differentiates odours, should find some odour repugnant, and that odour be beneficial to the human body? Absurd! Impossible! In the same way, could the human body, through the faculty of sight--the differentiator among things visible--benefit from gazing upon a revolting mass of excrement? Never! Again, if the sense of taste, likewise a faculty that selecteth and rejecteth, be offended by something, that thing is certainly not beneficial; and if, at the outset, it may yield some advantage, in the long run its harmfulness will be established.

And likewise, when the constitution is in a state of equilibrium, there is no doubt that whatever is relished will be beneficial to health. Observe how an animal will graze in a field where there are a hundred thousand kinds of herbs and grasses, and how, with its sense of smell, it snuffeth up the odours of the plants, and tasteth them with its sense of taste; then it consumeth whatever herb is pleasurable to these senses, and benefiteth therefrom. Were it not for this power of selectivity, the animals would all be dead in a single day; for there are a great many poisonous plants, and animals know nothing of the pharmacopoeia. And yet, observe what a reliable set of scales they have, by means of which to differentiate the good from the injurious. Whatever constituent of their body hath decreased, they can rehabilitate by seeking out and consuming some plant that hath an abundant store of that diminished element; and thus the equilibrium of their bodily components is re-established, and they are rid of their disease.

At whatever time highly-skilled physicians shall have developed the healing of illnesses by means of foods, and shall make provision for simple foods, and shall prohibit humankind from living as slaves to their lustful appetites, it is certain that the incidence of chronic and diversified illnesses will abate, and the general health of all mankind will be much improved. This is destined to come about. In the same way, in the character, the conduct and the manners of men, universal modifications will be made.