This chapter deals with group of patients in order to determine other factors which measurably impair the actualization of intellectual processes following lesions of the frontal lobes. These factors are general inactivity and the pathological inertness of established stereotypes. Such intellectual impairments are particularly typical of patients suffering from the frontal syndrome. It discusses lesions of the posterior-frontal areas of the left hemisphere. They cause the pathological inertness of established stereotypes, which is especially evident in the verbal sphere. The chapter also discusses more massive lesions when the pathological inertness of higher mental functions is more conspicuous and goes beyond the difficulty in performing individual intellectual operations. In these cases we observe severe disorders of the entire structure of intellectual activity. We may assume that many impairments, observed in the patient's intellectual activity, are caused by the pathological inertness of his speech.