In April 1884 Freud read of a German army doctor who had successfully employed cocaine as a means of increasing the energy and endurance① of soldiers. He determined to obtain some for himself and try it as a treatment for other conditions—heart disease， nervous exhaustion and morphine addiction. It was little known at that time and the extensive ethical and methodological rules governing modern drug trials did not exist.
Freud took some himself and was immediately impressed with the sense of well-being it engendered②， without diminishing his capacity for work. Having read a report in the Detroit Medical Gazette concerning its value in the treatment of addictions③， his next step was to recommend the substance as a harmless substitute to his friend and colleague， Ernst von Fleischl Marxow Fleischl， who had become a morphine addict following repeated therapeutic administrations for intractable④ neurological pain and was in desperate straits， took to cocaine with enthusiasm and was soon consuming it in large quantities.
Meanwhile Freud continued to extol the virtues of the drug， writing a review essay on the subject， taking it himself and pressing it upon his fiancee⑤， friends as a panacea for all ills. He had gone overboard with enthusiasm， writing to Martha when he heard she had lost her appetite，“Woe to you， my Princess. When I come. I will kiss you quite red and feed you till you are plump. And if you are forward you shall see who is the stronger， a gentle little girl who doesn’t eat enough or a big wild man who has cocaine in his body.”
Among the people to whom Freud introduced cocaine was his colleague Carl Koller， a young doctor working in the department of ophthalmology. Freud published his essay in the July issue of the Therapy， concluding it by drawing attention to the possible future uses of the drug as a local anaesthetic⑥. Koller was impressed， thought it likely to be useful in eye operations and two months later tried it out， first on animals and then on his own eyes with complete success. He was quick to publish his findings， thus securing a place in world history as the discoverer of what turned out to be virtually the only medical use for the substance.
Freud had missed his chance， but worse was to follow. Fleischl’s temporary improvement on taking cocaine was short lived. Within a week his condition deteriorated， his pain became unbearable and he relapsed into morphine consumption. He now had not one addiction but two， taking cocaine in doses a hundred times larger than Freud used to do. He suffered toxic confusional states in which he became agitated， experiencing severe anxiety and visual hallucinations. Yet Freud continued to advocate the use of cocaine in morphinism， presumably⑦ on the basis that （as had been reported by others） it was beneficial in selected cases.
His paper On the General Effect of Cocaine， written in the spring of 1885， was published in August and subsequently abstracted in the Lancer. By the following year， however， cases of cocaine addiction and intoxication were being reported from all over the world. Freud came under severe criticism for his advocacy of the drug and defended himself by claiming（inaccurately）that he had never advised its use in subcutaneous injections. He expressed the following view， “Theory is fine but it doesn’t stop facts from existing.” This became a favorite warning against the uncritical acceptance of received wisdom.
① endurancen. 忍耐，耐久力
② engenderv. 使产生，引起
③ addictionn. 沉溺，成瘾，上瘾，入迷
④ intractableadj. 不听话的，倔强的，棘手的
⑤ fianceen. ［法］未婚妻
⑥ anaestheticn. 麻醉药，麻醉剂
⑦ presumablyadv. 据推测，大概，可能，想必
弗洛伊德的发现
1884年4月，弗洛伊德读到一篇关于一位德国军医成功地使用可卡因来增加士兵体能和耐力的文章。他决定去搞一些并把它用于治疗心脏病、神经衰弱及吗啡嗜瘾等病症。当时这种药物鲜为人知，同时也没有像现代药品试用管理中广泛制定的道德上和使用上的规则。
弗洛伊德自己服用了一些，即刻就感到在不降低工作能力的情况下它所带来的快感。他在《底特律医学报》上读到一篇关于瘾品治疗价值的文章后，随即便向他的朋友和同事恩斯特·冯·弗雷氏马科斯科推荐了这种无害的替代物。弗雷氏由于患有顽固的神经方面的疾病而处境艰难，经过不断地药物疗法，他已嗜吗啡上瘾，当他充满热情地服用可卡因后，很快便开始大量使用。
与此同时，弗洛伊德继续颂扬这种药物的好处，写有关该药的评论文章，除自己服用外还把它当作灵丹妙药推荐给他的未婚妻、朋友们、同事们和病人们。他已然极度痴迷，当他听说玛撒没有食欲时便写信说，“唉，我可怜的公主。我回来后会热烈地吻你并使你吃得胖胖的。如果你乐意，你会看到谁更强壮，是一个胃口欠佳的柔弱女子还是一个体内充满可卡因的高大莽汉。”
在这些弗洛伊德推荐给可卡因的人中，有一位是他的同事卡尔·科勒，他是个年轻的眼科医生。弗洛伊德在7月份的《医疗专刊》上发表了一篇文章，在篇末他指出将该药用于局部麻醉的可能性。这给科勒留下了深刻印象，他觉得这可用于眼部手术并在两个月后开始试验，先是在动物身上，之后在自己的眼睛上，并取得了完全的成功。他即刻公布了这一发现，因此他作为在医疗实用中运用的唯一的该物质的发现者在世界历史上占有一席之地。
弗洛伊德失去了这次机会，但更糟的事又接踵而至。弗雷氏服用可卡因的短期效益没有持续多久。不出一周他的情况每况愈下，痛苦不堪同时又陷入服用吗啡的恶习。他现在不是只沉溺于一种而是两种，可卡因的服用量要比弗洛伊德当时大100倍。他遭受着中毒性的恍惚状态，变得焦躁不安，极度忧虑并产生幻觉。而弗洛伊德仍继续倡导在吗啡上瘾时服用可卡因，据其他人的报道这可能是建立在某些病症上会产生效应的理论基础上的。
他的论文《关于可卡因的普遍效应 》写于1885年春季，8月份发表后就在《持矛骑兵》杂志上登出摘要。可是到了第二年，世界各地都报道了可卡因上瘾及中毒的情况。弗洛伊德因倡导这种药物受到了严厉的批评，他为自己辩护道（不确切地）他从没建议过以皮下注射来使用它。他表达了如下的观点，“理论固然不错，但它无法制约已经存在的事实。”这对于全盘接受常理的人无疑是个良好的忠告。