When Albrect von Haller, the great physician of the eighteenth century, was for a time subsisting upon a strictly vegetarian diet, he felt great muscular weakness, a decided depression of spirits, and was unable to da any mental work. (As a proof of Haller’s intelligence, I would call attention to the fact that at the age of 5 years he was explaining the Bible to his father’s servants, and at 12 years wrote a Greek gram-mar.) Results similar to the above are often noticed. Personally, I experienced the same effects after a long-continued vegetable diet. Undernutrition often leads to excitability of the nervous systemmany cases of nervousness, neurasthenia, and hysteria are improved by a plentiful dietand the disinclination for mental labor may perhaps be due to this. According to the statements in the previous chapter, the lack of phosphorus may possibly be the chief factor in such conditions, since the nervous system cannot properly carry out its functions without a sufficient quantity of phosphorus. As already stated, the phosphorus of animal origin is better assimilated; in a vegetable diet much of it is lost in the intestine. Fish is preferable to meat, since, according to the recent works of Slowzoff, the salts are more readily absorbed from it and the phosphorus content in the body is therefore increased. Up to the present the impression has prevailed that the amount of phosphorus in fish is small ; but when we study the analyses of Balland and Jebbink, it will be seen that some quite small fish have a particularly high phosphorus content. According to Balland, fried gudgeons contain more of it than perhaps any other food substance, the natural substance containing o.82 per cent. of phosphorus and 0.90 per cent. of phosphoric acid ; thus more than twice the amount in meat. The same is the case in some other fish varieties, according to Jebbink. The experiments of Schmidt and Bessau also show that the smaller fish have a high nuclein content and consequently contain much phosphorus. Leguminous vegetables and cereals are likewise rich in phosphorusaccording to Balland, they surpass many of the small fish in this respectbut a considerable portion of this substance passes through the intestine unused when a pure vegetable diet is partaken of. There is probably no article of food poorer in phosphorus than the fine white bread so much used by the wealthier classes, and Aron and Hodgeson have shown that monkeys gradually weaken and die upon such a diet. The same was the case with the animals of Forster, Eickman, Axel Holst, and others when fed upon food lacking in phosphorus. We must not imagine, however, that an untalented writer will become a Victor Hugo if he continually feeds upon fish, eggs, meat, and cheese and leguminous vegetables in particular, since the intellect does not only depend upon this, but also upon the condition of certain organs which exert a great influence upon the phosphorus metabolism. The American humorist, Mark Twain, wrote to a young writer of average capability-who had asked his opinion in regard to some of his writingsthat he would do well to eat a whale every day, by which means he would become a celebrated author, since it was said that a fish diet had a stimulating effect upon the mental attributes.
At all events, a fish diet is efficacious in mental labor owing to the fact that it is very easily digested; this is of great importance, for after a plentiful meal of meat one feels heavy and brainwork is accomplished with difficulty. The same may be said of any very full meal, especially if the food is difficult to digest. During the digestion more blood flows to the digestive organsas it does to any organ which is at workand consequently less to the brain. While an overabundant diet may be injurious, an insufficient one is much more so, since the quantity and quality of the blood, as well as the circulation of the brain, suffer thereby. Moreover, a great loss of phosphorus always occurs in undernutrition. It will thus be readily understood what serious injury is inflicted upon growing school children when they are allowed to go hungry. When, therefore, the State renders attendance at school compulsory, it should likewise see to it that every child be properly nourished. A starving school child puts the modern State administration to shame. When there is a question as to who should do without food, it should rather be the father than the child who is obliged to study. The poor, hollow-cheeked student, who has not enough to eat and who has many difficult subjects to study, is one of the greatest reproaches to our civilization and culture. If such children were given a certain amount of food at the expense of the State, the money spent for this purpose would be returned a hundredfold, when we consider that in this way very useful citizens would be trained, and much money now spent for the maintenance of hospitals, workhouses, and prisons would be saved. Unfortunately, so many proviso’s of the modern State government are reparative, but not preventive. Millions are spent where as many thou-sands would have sufficed if matters had been attended to in time.
By innumerable trials upon cretinous school children, it has been made clear that they are markedly benefited by the thyroid treatment. Possibly the results would be even more satisfactory if phosphorus and lime were to be administered at the same time in the food. Such a diet would even be indicated for normal children, as the physical growth is likewise increased by it. As an important constituent of this diet should be included bread made from whole wheat, which is more rich in phosphorus. The thyroid gland cannot stimulate either the intelligence or growth, if there is not at the same time a sufficient amount of phosphorus and lime in the food.
The diet of a brainworker should be one adapted to the nature of his work. In view of the considerations already presented it would perhaps be advisable to make experiments for the purpose of elucidating how certain kinds of mental labor are affected by various foods. When creative work is to be donethe formulating of new, original ideasa meat and fish diet, with eggs, cheese, and green vegetables, might be the best. Thus, for musical composers, writers, etc., such a diet, with meat and fish once a day, would be indicated, as well as for scholars who are endeavoring to elaborate some new creative ideas. When it is desired, however, to work untiringly with a clear head and quiet mind in carrying out the details of an already established program, no other diet is so suitable as the milk-egg-vegetable one, with meat excluded, or a purely vegetarian diet. For a merchant who wishes to speculate or carry out some new undertaking, a diet with meat and fish once a day is well adapted. Bookkeepers or cashiers, who must work at figures with a clear head, as a mistake made might cause great damage, will do well with a vegetable diet, and the same will be the case with officials, providing they adhere strictly to the one régime. Their industry would greatly exceed that of the meat-eaters. Even the “boss” would do better on a milk-egg-vegetable diet, and would frequently lose less in his speculations and combinations. As an illustration of the above in the animal kingdom I would like to mention the fact that a hunting dog which must scent out and point the game should be given some meat every day in order success-fully to perform his task. For the cart-dog, which sometimes has to pull about quite heavy burdens, more carbohydrate food is required, although some meat would also be advantageous. Physical labor is principally carried on at the expense of the carbohydrates, whereas mental work cannot be accomplished without a sufficient or rather an abundant supply of albumin, According to Pflüger and Rubner, albumin is the greatest producer of energy.
I cannot imagine such a man as Napoleon living upon a purely vegetable diet, and I think that everyone will agree with me. It certainly was not the case, and he was a very impulsive eater. He ate at all hours, and food had constantly to be kept prepared and ready for him; he was most surely not a methodical, temperate man, as he might have been upon a vegetarian diet, but a true genius !
From these considerations it follows that for nervous, restless persons and for quiet, methodical mental work no diet is superior to the vegetarian. For the pursuit of new fields of endeavor, the creation of new inventions, etc., this would, however, probably not be the case.
It is exceedingly difficult to generalize, and in this still rather obscure field we must be especially careful in coming to conclusions. One thing is certain, however, viz., that where mental work is to be accomplished moderation in eating and drinking is necessary. It would be advisable rather to eat more frequently than to wait until ravenously hungry and then eat too much, thus rendering one’s self heavy and unfit for any work. It is best to take a glass of milk, with a little cream and the yolk of an egg added; for when we consider how rich in fat the brain (up to 8 per cent.) and the nervous system (21 per cent.) are, we shouldif the principle that for the proper functioning of an organ the substances in which it is rich should be administered in considerable amounts is correcttake plenty of milk, butter, and eggs while mental labor is being carried on, since the organs in question contain much lecithin.
When the milk-egg-vegetable dietwhich is in the average case the proper one, except under the circumstances above mentionedis used, milk, oatmeal gruel, or some other of the breakfast dishes previously referred to, such as eggs, fruit (cherries), etc., should be taken. At noon thick vegetable soups, eggs, cheese, vegetables, macaroni, milk, stewed fruit are suitable; in the evening, eggs, cheese, vegetables, macaroni, or rice. Altogether this gives an average daily of 4 to 6 eggs, z to 1y2 liters of milk, with cheese, macaroni, rice, sago, green vegetables, and fruit (nuts, raisins, dates, and fresh fruits). When, for the reasons mentioned, a mixed diet is taken, meat may be eaten at noon and fish in the evening. As a beverage cocoa, which is especially rich in phosphorus, should be used; this was the favorite drink of the great Swede, Karl Linnæus (Linné).