There are two basic types of mental activity. One is pictorial,non-rational and emotional, and concerns the biologicalfundamentals of birth, attachment, sex, separation anddeath, as well as art and creativity; the second is rational,verbal and logical and concerns the achievement of specificgoals and the solving of particular problems. Freud calledthese the primary and secondary processes. Non-rationalthinking is primary because it precedes rational thinkingdevelopmentally: infants and young children think in feelingsand pictures. The secondary processes are only graduallyacquired. In healthy adult life both coexist. Much ofwaking life is dominated by secondary processes, but indreams, daydreams and instinctual activity the primaryprocesses take over. In mental illness the balance ofprimary and secondary processes may be disturbed: thepsychotic, for example, is dominated by primary processes,whereas the patient with obsessional neurosis is tryingto apply the false logic of secondary processes to hisemotions.Modern medicine is based on scientific rationality. Thismeans that at times doctors may find it difficult to comprehendthe emotional reactions of the patient to illness,death or sexuality. For the doctor, the patient who needsa routine hernia operation presents a technical problemto be solved; the patient, however, may at some level bewondering whether he will survive the operation and, if so,whether his sex life will continue. Medical training is predominantlya training in rationality, in learning to set feelingsaside. In order to understand the 'irrational' anxietiesthat trouble patients the doctor has to remain in touch withand respect the primary processes. The following sectionson sex, and on death and dying, highlight some of theseissues.