This chapter explores the nature of Sigmund Freud ideas associated with the second arm of the fulcrum of diagnosis—the mechanisms of the neuroses in general. Many changes occur in his ideas of the mechanisms involved, even in his earliest years as a clinician. Freud suggests a powerful defence, one in which the ego rejects the incompatible idea together with its affect and behaves as if the idea had never occurred to the ego at all. The defence theme broadens quickly at the period of fertile theory construction, with the mechanism of psychoses, too, being that of defence, but now with greater acuity The problem of how anxiety arises in connection with repression is not simple, but regardless, it is still the ego that is the agent of the repressive process. The mechanisms of splitting are no longer a simple matter but conceptualized as a number of processes that are distinguishable by virtue of the variety of their pathological effects.