That all men and women feel the weariness of life is testified by the fact that the people of all nations and all climes have the universal habit of daily seeking a restorative and stimulant in one of the vegetable products which contain a substance or alkaloid capable of exercising a definite effect on the nervous and cardiac systems. Thus, the Chinese and Japanese sip their tea, and the English, following their example, brew the five o'clock cup of the fragrant herb to sustain them in the day's work, the Arab and Turk seek, like the French and Germans, restorative powers in the aromatic coffee berry, the Cingalese chew the betel nut, and the natives of Peru on the slopes of the Andes find in coca leaves a principle which sustains the body in fatigue and comforts the mind in hopelessness. Von Bibra says of coca: "It satisfies the hungry, lends new strength to the weary and fatigued, and makes the unhappy forget his grief". What, then, is this strange substance which seems to conceal a fairy's wand? We shall find, however, that, resembling other fairy wands for the cure of the plagues of life, it may turn, like the magician's rod, into a viper.

Coca is obtained from the leaves of a shrub-like plant called the erythroxylon coca; it is a native of Peru and Bolivia, where it has been cultivated with the greatest care from the remotest antiquity. When Peru was conquered by the Spaniards in the sixteenth century, and the ancient and interesting people of this country were discovered, it was found that their Incas or kings looked upon the cultivation of the coca plantations as a public and national duty, and also that the strange custom prevailed among the Peruvians of chewing the leaves of the coca plant during frequent and short periods of repose, specially set aside for this purpose. This custom prevails to this day among the half-bred Indians of Peru and Bolivia. Three or four times a day the Indian, labouring in the mines or on the plantations, retires from work, and, lying down in a comfortable position, draws from a leather pouch a few leaves of coca; these he rolls into a ball, which he puts into his mouth and slowly chews, adding from time to time a small amount of unslaked lime, which is said to bring out the true flavour of the leaf. The chewing causes a copious flow of saliva, which is swallowed, but the masticated leaves are rejected when all they contain has been thoroughly extracted. The Indian of the Andes is by nature gloomy, taciturn, and melancholy; but when chewing the coca leaf in repose he seems to be in a condition of passive happiness, and to be removed for a short time from the depressing effects of the toil, the poverty, and the hardship of his lot. The indulgence in coca may be pushed to the extent of intoxication, or the habit of chewing may enslave a man; but these cases are not common among the Indians.

The physical effects of coca are, however, more salutary and in many respects more remarkable than the mental. It is universally acknowledged that coca stills hunger, overcomes drowsiness, and increases bodily activity. All travellers in the Andes bear testimony to the wonderful power shown by the Indians to endure fatigue, cold, wet, and exposure, with only the scantiest allowance of poor food, if they are supplied with coca. The life of the Indian of the Andes is one of extraordinary toil and hardship. His diet consists mainly of a small quantity of maize and frost-dried potatoes; he is constantly exposed to the intense heat of the plains or to the terrible cold of the high plateaus of the Cordilleras; the toil exacted of him in the mines and the plantations is excessive; but he is yet able to perform, not exceptionally, but constantly and as a matter of daily life, the most astonishing feats of endurance on a diet which would be absolute starvation to a European, or to exist even for a time without food at all, by the aid of the power which coca gives. Von Tschudi, the naturalist and traveller, gives a remarkable account of an Indian, sixty-two years of age, who was employed by him in digging for five days and nights, with only an interval of sleep of two hours each night. During this time it is asserted that he never tasted food, though at intervals of from two to three hours he chewed half an ounce of coca leaves. The work done, he accompanied Von Tschudi on foot through a two days' journey of seventy miles across the level heights, halting only to chew his coca. The most striking stories are told of the men engaged in the postal service, who, half-naked, traverse the icy slopes of the Andes carrying the heavy mail bags. These men walk from 200 to 300 miles, crossing the mountain by paths rising 13,000 and 14,000 feet above the sea level; their scanty clothing being a poor protection against the fierce snowstorms, the intense cold and the rarefied air of the Andes. Their food for the journey consists of from one to two pounds of dried maize and potatoes; but if supplied with sufficient coca to chew they endure cold, hunger, fatigue, and sleeplessness not only without complaint, but without even seeming to be aware of them. In like manner the Indian labourers in the mines of the Cordilleras, whose toil is spoken of as incessant and excessive, and performed in damp, cold, and darkness; the shepherds tending their flocks of alpacas on the bleak Pampas, and the farmers irrigating their fields at night in mid-winter on the high plateaus, standing often knee-deep in icy water and exposed to cutting blasts, are all said to be equally inured to a life of surprising hardship and privation, by the daily use of coca. It is stated, however, that though no hermit or monk ever lived so ascetic a life as these poor Indians, yet the appetite for food is only stayed, not destroyed by coca, and that if any one is kind and generous enough to feed them, they eat with voracity and evident enjoyment. It is also said that if they change their food and give up coca they lose their power of endurance; and, moreover, that the Spaniards who go to work in the mines cannot stand the great hardships of the life and the inclemency of the Cordilleras till they take to the regular use of coca. Von Tschudi tells us that this life of silent endurance and bitter abnegation may be much prolonged, even in one instance to 130 years.

The other remarkable effect of coca is the influence it exercises on the respiratory centres, so that the rarefied air of the higher altitudes of the Andes can be breathed without the distress usually experienced at the height of thirteen or fourteen thousand feet above the sea. All travellers speak of the extraordinary way in which the Indian porters will keep up with the quick pace of the mule along the roughest mountain paths without showing any signs of breathlessness.

Though wonderful but little credited stories were told for two centuries of the staying power of coca leaves, no attempt was made to introduce them into Europe, and scientifically to test their value either as dietetic or therapeutic agents till about forty years ago. The first experiments were nugatory, as the substances which give the leaves their subtle power escaped or were volatilised during the voyage. Care has, however, since been taken to enclose the leaves in air-tight boxes, with the result that a great variety of fluid extracts and wines of coca are now made, and are widely recommended for their tonic properties.