The part played by reason in society has fundamentally changed. 'Reason, in destroying conceptional fetishes, ultimately destroyed itself.' 'None of the categories of rationalism has survived.' The consequences and causes of this fact are investigated by Horkheimer. The consequences are seen in various fatal disintegrating changes in cultural achievements, especially in the annulment of all individual autonomy in 'mass culture'. The causes are to be seen in changes in the realm of the material basis of society. The reviewer had the impression that Horkheimer overstresses technology, machine age, common production and the fact that the grandeur of the big machines turns the human being into a dwarf, instead of emphasizing the use which is made of technology, machine age, and common production under the present conditions of accumulation, distribution, and consumption.