Considering aspects of symmetry rules in chemistry, one is faced with con tradictory terms as for example, "90 % concertedness" sometimes being used in literature. To accept conservation of orbital symmetry to be as controlled as inversion by alternative principles seems far more promising. The intention of this book is aimed at introducing a qualitative understanding of phase rela tions in electromagnetic interactions. Avoiding one-sided dogmatism we tried to demonstrate the importance of alternative principles as guidelines to the evolution of alternative order in chemical systems. Passing...