The opening of the text includes a foreword in which Vorländer explains his motivations for delivering a series of university lectures on the philosophies of the mentioned authors. He emphasizes the importance of returning to the foundational ideas of these figures in the context of contemporary philosophical challenges. Vorländer expresses his admiration for the clarity and rationality found in the works of these writers, particularly in their approaches to ethics, religion, and aesthetics. He sets the stage for a deeper exploration of each thinker, starting with Lessing, whose early life and engagement with religious philosophy are briefly introduced, foreshadowing a detailed analysis of his thought and its significance. (This is an automatically generated summary.)