"The physiology of the action of alcohol has a very practical bearing on the physical regimen of the mental functions. Alcohol has the power of curbing, arresting, and suspending all the phenomena connected with the nervous system. We feel its influence on our thoughts as soon as on any other part of the man. Sometimes it brings them more completely under our command, controls and steadies them; sometimes it confuses or disconnects them; then breaks off our power and the action of the senses altogether. The first effect is desirable, the others to be avoided. When a man has tired himself with intellectual exertion a moderate quantity of alcohol taken with food acts as an anaesthetic, stays the wear of the system which is going on, and allows the nervous force to be diverted to the due digestion of the meal. But it must be followed by rest from mental labour, and is, in fact, a part of the same regimen which enforces rest—it is an artificial rest. To continue to labour and at the same time to take the anaesthetic is an inconsistency. It merely blunts the painful feeling of weariness, and prevents it from acting as a warning. I very much doubt the quickening or brightening of the wits which bacchanalian poets have conventionally attributed to alcohol. An abstainer in a party of even moderate topers finds their jokes dull and their anecdotes pointless, and his principal amusement consists in his observation of their curious bluntness to the groundlessness of their merriment. There is no more fatal habit to a literary man than that of using alcohol as a stimulant between meals. The vital powers go on getting worn out more and more without their cry for help being perceived, and in the end break down suddenly, and often irrevocably. The temptation is greater perhaps to a literary man than to any other in the same social position, especially if he has been induced by avarice, or ambition, to work wastefully against them; and if he cannot resist it, he had better abjure the use of alcohol altogether…. Mental activity certainly renders the brain less capable of bearing an amount of alcohol, which in seasons of rest and relaxation does not injuriously affect it. When any extraordinary toil is temporarily imposed, extreme temperance, or even total abstinence, should be the rule. Much to the point is the experience of Byron's Sardanapalus:—

"The goblet I reserve for hours of ease, I war on water."

"It is true that Byron assumes in his poetry the character of a debauche, and says he wrote Don Juan under the influence of gin and water. But much of that sort of talk is merely for stage effect, and we see how industrious he was, and read of his training vigorously to reduce corpulence, and of his being such an exceptionally experienced swimmer as to rival Leander in crossing the Hellespont…. The machinery of sensitive souls is as delicate as it is valuable, and cannot bear the rough usage which coarse customs inflict upon it. It is broken to pieces by blows which common natures laugh at. The literary man, with his highly-cultivated, tightly-strung sensations, is often more than others susceptible of the noxious, and less susceptible of the beneficial results of alcohol. His mind is easier to cloud, and there is a deeper responsibility in clouding it…. Equally when we descend into the lower regions of Parnassus, the abodes of talent and cleverness, and the supply of periodical literary requirements, we find the due care of the body absolutely essential to the continued usefulness of the intellect. The first thing to which one entering the profession of literature must make up his mind is to be healthy, and he can only be so by temperance…. Tobacco should not be indulged in during working hours. Whatever physiological effect it has is sedative, and so obstructs mental operations."

Manual of Diet in Health and Disease. 1876, p. 162.