This section is from the book "Health Without Medicine. A Treatise On The Laws Of The Human System", by Larkin B. Coles. Also available from Amazon: Philosophy Of Health.
Those who accustom themselves to intellectual labor require habits of living somewhat different from those who are engaged in pursuits of a physical character. Though all should strictly obey the laws of their natures, physical and intellectual, yet, while some habits of living may be lawful, they may not be, under certain conditions in life, expedient; and indeed what may be lawful for one, under certain circumstances, may not be lawful for another under other circumstances. For instance, as before stated, a person engaged in farming can bear the evil effects of animal food better than one of sedentary and literary habits. Since meat-eating, according to general admission tends to oppress and check mental development, it becomes inexpedient, if not unlawful, for persons devoted strictly to intellectual pursuits, to practise it. It is doubtless inexpedient for any to use it; but in the case of those whose skill and usefulness depend upon an unclouded and active intellect, this inexpediency comes near the range of moral obliquity.
For a sample of the effects of meat-eating, on a large scale, upon the intellect, see the difference between the French and English, in regard to their habits and character.
The English are inclined to gluttony; they are enormous meat-eaters; they take meat largely at each of their meals. They are generally inclined to be of the lymphatic temperament; a consequence of habitual stuffing with roast-beef, beef-steaks, and plum-puddings. And what is the effect upon the mass of mind? While we find some highly gifted, commanding, and high-toned geniuses, the mass are stupid and comparatively unintelligent.
The French live principally on vegetables; they generally possess the nervous temperament; a temperament adapted to literary and intellectual habits. They have quick and energetic minds. They have a large flow of spirits, great vivacity and cheerfulness, and are remarkably effective and productive in their mental character. It is well known that a very large proportion of various scientific works have originated from France. The science of medicine, with various collateral sciences, is highly indebted to the wakeful genius and indefatigable zeal of French intellect for its advancement.
Professional and literary men should live on simple, nutritious, and regular diet. The less exciting their food, the better; the less meat -- if none at all -- the better; in short, they should observe all the rules of diet previously laid down. They should by no means use stimulating drinks. Their nervous systems are more severely taxed than many other classes of men: hence the absolute necessity of economizing the nervous strength; and if they would preserve that, they must not suffer their nerves to be artificially and unnaturally excited. They should have wholesome nourishment, and then let nature herself supply her own well-balanced excitement.
The clergymen of this country, in days long since -- as now in England -- were accustomed to prepare and preach their sermons under, and in demonstration of, ardent spirit. Now, among us, this method is abandoned; but there is a substitute which answers precisely the same purpose, and is even better; for when the ardent was used too freely -- which not unfrequently occurred -- the subject would reel under the weight of his accumulated ideas; while the subsititute equally inspires the brain, without causing the zigzag and horizontal motions. That substitute is tea: or, it may be, coffee. The nature and effects of these articles have been already examined, and it is not necessary to dwell upon them here.
When the writer was a settled pastor, a few years since, in a neighboring town, he was accustomed to have, on entering his study, extreme nervous depression -- sinking of the nervous energies -- insomuch that it was impossible to make any mental effort while in that state; a bowl of tea, therefore -- in accordance with previous habits -- would be ordered; on taking which, the extreme depression would immediately pass away, and a most cheerful and happy flow of spirits would take its place. Under this a sermon could easily be prepared; 'and on the Sabbath, under the same kind of stimulus, it could be preached. But a little time of such violation of law developed the fearful fact that nervous debility and depression were rapidly increasing -- that the more stimulus that was taken, the more must be taken to meet the demand. Hence, the tea was abandoned entirely; and very soon the complaint disappeared, and has returned no more. This is an illustration only of facts which always will exist in every instance of tea-drinking under similar circumstances, whether they be readily perceived or not. How much better in every case, and especially in that of ministers, that they depend, in all their intellectual labors, on the real, substantial, and uniform inspiration of nature, than upon the spurious, fitful, debilitating excitement of some foreign stimulant. How much better that the ministers of Christ, under such solemn and awful responsibilities as the preaching of the gospel involves, lean on the divine energy of the Holy Ghost, than on the transient energy of some artificial excitement; nay, how profane and wicked is such a departure from nature and from nature's God.
The injurious effects of tea and coffee cannot be resisted by the habits of professional men, as much as by the habits of the laboring classes. They must either abandon them altogether, or bow down as slaves to appetite, and take the consequences. They must abandon them, or consent to have less health of body and mind, and die sooner. See the sallow complexion and trembling hand of the barrister, especially as he advances in life, who, instead of living naturally, has lived artificially all his days; will he continue to barter his highest earthly good for such pottage? He may live to old age; and so may the drunkard.