 The understanding of reason as one and universal embodied in the works discussed in the preceding section also informs the approach taken by Feuerbach to the history of philosophy in the three previously mentioned books and a series of lectures that he produced during the  1830s.[8]  In his lectures on the history of modern philosophy Feuerbach emphasizes that philosophical reflection is an activity to which human beings are driven. The history of the philosophical systems that this activity has produced, he argues, is conceived only subjectively and thus inadequately as long as it is regarded as the history of the opinions of individual thinkers. Because thinking is a species-activity the philosophical systems that have arisen in the course of the history of philosophy should be regarded as necessary standpoints of reason itself. The Idea is not something first produced by philosophical reflection. Rather, the individual thinker, in the act of thinking, transcends his individuality and functions as an instrument or organ through which the Idea actualizes one of its moments, which is later reproduced in the consciousness of the historian of philosophy. The activity of the Idea is experienced subjectively as inspiration (Begeisterung). In producing itself, the Idea does not pass from nonbeing into being, but rather from one state of being (being in itself) to another (being for itself). The Idea produces itself by determining itself, and human consciousness is the medium of its self-actualization. 