Psychoanalysis is a method and technique of therapy for mental and emotional disorder, around which there has evolved a definite body of theory. From 1910 to 1920 S. Freud also was gradually evolving a new theory granting etiological importance to factors other than sex. Increased study of comparative cultures in the late 1920's eventually contributed significantly to another challenging of Freud's biological theory of neurosis by the so-called cultural school of analysts, whose thinking began to influence psychoanalysis around 1934. Freud, who was critical of so many false beliefs and practices of his time, seems to have accepted without question the idea that parents always loved their children and that the child's fears and difficulties were chiefly due to his own innate impulses. The successful application of theory to therapy was limited to a few types of cases, although as knowledge of psychoanalysis was spreading people with all kinds of emotional difficulties were seeking treatment in increasing numbers.