"The ticquer has a strong sexual attachment; this is so strong that the love instinct ineffectually sublimates the hate instinct and in the warring conflict doubt and physical and psychic inadequacy arise. The situation continues and generates mental, and physical infantilism, which in turn make for increased feelings of tension. Motor and psychic restlessness succeed. The motor expression manifests itself most often in habit movements of disguised sexual significance (autoerogenous pleasures) a form of physical stereotypy, in its broadest psychophysical meaning. The mental state often pari passu takes up obsessive thinking and various physical acts and thoughts are formed as defense mechanisms, born of conscious guilt. The motor habits are usually inhibited or displaced in part, and the tic remains as a motor symbol, usually in itself non-sexual, as a fragment of the former complete habit movement. The mechanism of the completely evolved tic is either a conversion (hysteric) or substitution (obsessive) mechanism or both." By these who have studied Freudism this will, in a way, be understood. For these who have not it may be more difficult of understanding without somewhat further elaboration or explanation. In this connection I must again mention that the Freudians include tics under their obsessive (obsessional) neuroses. The theory of the mental mechanisms and evolution of these states is given in the attached quotation, which is taken verbatim from Clark's paper. "The affect of the painful idea does not become transformed into physical symptoms, as in the conversion mechanism of hysteria, but affixes itself to other ideas not in themselves unbearable, thus producing by this false relationship a substitutive symptom or obsession.