The author tries to build up her theory of æsthetics on a biological basis. She considers that in the course of evolution man loses much of his instinctive capacity, exchanging this for a greater adaptability to various outside changes. The result is a sense of insecurity, originating in an ambivalence of feeling toward any experience, since every experience in the outside world brings with it an alternation of attraction and repulsion. The æsthetic experience

brings man a brief illusion of completeness, 'of knowing a whole', bringing with it a regression to the purely instinctive sphere of the prenatal existence. Art causes a regression to the purely instinctual level of experience (instinct in the sense of the German word Instinkt, not Trieb). From this standpoint the author examines the phenomena of natural beauty, imagination, genius, form and taste.