So we come to the question, why does the libido make a regression? To answer it we must study carefully under what circumstances regression arises. In treating this problem with my patients, I generally give the following example: While a mountain climber is attempting the ascent of a certain peak, he happens to meet with an insurmountable obstacle, let us say, some precipitous rocky wall which cannot be surmounted. After having vainly sought for another path, he will have to return and regretfully abandon the climbing of that peak. He will say to himself: “It is not in my power to surmount this difficulty, so I will climb another easier mountain.” In this case, we find there is a normal utilization of the libido. The man returns, when he finds an insurmountable difficulty, and uses his libido, which could not attain its original aim, for the ascent of another mountain. Now let us imagine that this rocky wall was not really unclimbable so far as his physique was concerned, but that from mere nervousness he withdrew from this somewhat difficult enterprise. In this case, there are two possibilities: I. The man will be annoyed by his own cowardice, and will wish to prove himself less timid on another occasion, or perhaps will even admit that with his timidity he ought never to undertake such a difficult ascent. At any rate, he will acknowledge that he has not sufficient moral capacity for these difficulties. He therefore uses that libido, which did not attain its original aim, for a useful self-criticism, and for sketching a plan by which he may be able, with due regard to his moral capacity, to realize his wish to climb. II. The possibility is, that the man does not realize his own cowardice, and declares off-hand that this mountain is physically unattainable, although he is quite able to see that, with sufficient courage, the obstacle could have been overcome. But he prefers to deceive himself. Thus the psychological situation which is of importance for our problem is created. The Etiological Significance of Failure of Adaptation