The task of this theory of knowledge is not to examine the conditions for the possibility of any knowledge, nor the prerequisites for knowing, whether formal or material, but to investigate the act of knowing itself. The fact that something is recognized, i.e., that objects are grasped in perceptions, memories, thoughts, doubts, beliefs, and knowledge, serves as the starting point for the following considerations. The questions that need to be answered by the psychology of knowledge include how the various forms of knowing differ from one another, what elementary processes they consist of, and what laws govern their development. The Publishing House of Sciences publishes historical literature by both well-known and lesser-known scientific authors, thereby making works that have long been out of print accessible again to interested readers.