With theory, one can frighten readers. And with theory, some authors frighten themselves. This book attempts to avoid both. It gathers essays that strive for a gentle introduction to the legendary systems theory while almost imperceptibly increasing complexity. Resistance is deliberately sought, the concept of action is clarified, the relationship to networks is discussed, and negativity is introduced. The question of what can be achieved with texts of this kind is also not overlooked: What is the purpose of a theory that accepts and simultaneously restricts the belief in causality? How can one escape mysticism under these conditions?.