[9] The philosopher Friedrich Nietzsche described Hartmann's book as a "philosophy of unconscious irony", in his On the Use and Abuse of History for Life, one of the essays included in Untimely Meditations (1876).

[12] The psychiatrist Henri Ellenberger writes in The Discovery of the Unconscious (1970) that the main interest of Hartmann's work is not its philosophical theories, but its wealth of supporting material.

[2] The psychologist Hans Eysenck writes in Decline and Fall of the Freudian Empire (1985) that Hartmann's version of the unconscious is very similar to Freud's.

He credited Hartmann with offering a "canny and vigorous" description of sexual desire, but nevertheless considered him unsuccessful in explaining its intentionality.

[14] The Italian poet Giovanni Pascoli was influenced by Philosophy of the Unconscious in his poetics program, "Il fanciullino" ("The child", 1897).