incompetence, they always lack insight into their situation. Peter and Hull go on to explain why aptitude tests do not work and are actually counter-productive. Finally, they describe "Summit Competence": when someone reaches the highest level in their organization and yet is still competent at that level. This is only because there were not enough ranks in the hierarchy, or because they did not have time to reach a level of incompetence. Such people often seek a level of incompetence in another hierarchy; this is known as "Compulsive Incompetence." For example, Socrates was an outstanding teacher but a terrible defence attorney. Chapter 10 explains why attempts to assist an incompetent employee by promoting another employee to act as their assistant does not work: "Incompetence plus incompetence equals incompetence" (italics in original). Chapters 11 and 12 describe the various medical and psychological manifestations of stress that may come as result of someone reaching their level of incompetence, as well as other symptoms such as certain characteristic habits of speech or behaviour. Chapter 13 considers whether it is possible for an employee who has reached their level of incompetence to be happy and healthy once they get there: the answer is no if the person realizes their true situation, and yes if the person does not. Various ways of avoiding promotion to the final level are described in chapter 14. Attempting to refuse an offered promotion is ill-advised and is only practicable if the employee is not married and has no one else to answer to. Generally, it is better to avoid being considered for promotion in the first place, by pretending to be incompetent while one is actually still employed at a level of competence. This is "Creative Incompetence," for which several examples of successful techniques are given. It works best if the chosen field of incompetence does not actually impair one's work. The concluding chapter applies Peter's Principle to the entire human species at an evolutionary level and asks whether humanity can survive in the long run, or will it become extinct upon reaching its level of incompetence as technology advances. Research and related works Other commenters made observations similar to the Peter principle long before Peter's research. Gotthold Ephraim Lessing's 1763 play Minna von Barnhelm features an army sergeant who shuns the opportunity to move up in the ranks, saying "I am a good sergeant; I might easily make