In these essays Heinz von Foerster discusses some of the fundamental principles that govern how we know the world and how we process the information from which we derive that knowledge. Included are path- breaking articles concerning the principles of computation in neural nets (1967), the definition of self-organizing systems (1960), the nature of cognition (1970), as well as recent expansions on these themes (e.g. "How recursive is communication," 1993). Working with Norbert Wiener, Warren McCullough, and others in the 1960s and 1970s, von Foerster was one of the founders of the science of cybernetics, which has had profound effects both on modern systems theory and on the philosophy of cognition. At the Biological Computer Laboratory at the University of Illinois he produced the first parallel computers and contributed to many other developments in the theory of computation and cognition.

Over the past years the author has developed a quantum language going beyond the concepts used by Bohr and Heisenberg. The simple formal algebraic language is designed to be consistent with quantum theory. It differs from natural languages in its epistemology, modal structure, logical connections, and copulatives. Starting from ideas of John von Neumann and in part also as a response to his fundamental work, the author bases his approach on what one really observes when studying quantum processes. This way the new language can be seen as a clue to a deeper understanding of the concepts of quantum physics, at the same time avoiding those paradoxes which arise when using natural languages. The work is organized didactically: The reader learns in fairly concrete form about the language and its structure as well as about its use for physics.