“Simon Friederich’s Therapeutic Approach to quantum theory (QT) sheds new light on the status of the quantum state. … The book not only provides interesting perspectives for the cognoscenti but is also written with sufficient care and free of unnecessary technicalities so as to be accessible and worth reading for the physical layman interested in the foundations of QT. … anyone interested in the foundational problems of QT should feel encouraged to investigate Friederich’s book himself, without question.” (Florian Boge, Erkenntnis, Vol. 82, 2017)