In radiesthesics, each individual person works on their own and its answerable only to themselves, so that a radiesthologist may be compared to a self-employed master craftsman. It is said that three things make a master, namely "Knowledge, experience and motivation." One may ask whether every radiesthologist can meet this challenge. Anyone restricting their use of the dowsing rod or pendulum solely to look for springs of water would only be burdening themselves needlessly by absorbing information on factors of disturbance and methods of removing harmful rays etc. This book is not for them: however, if anyone wants to know how to get rid of harmful rays that cause disturbance in the places where they live and work, or if they want to decide for themselves about the effectiveness o ray-protection appliances and methods, then they cannot do without sound specialist knowledge. The advice of a radiesthologist on how to avoid ray disturbance by altering the layout of the room or the arrangement of the furniture etc. cannot in the long run meet the requirement for complete freedom from harmful rays, because fields of disturbance stemming from water-courses may build up and may appear and disappear depending on the level of the water table; and in addition, it is completely impossible to take into account the alterations in the influence of factors of disturbance all around us. In a flood, a tree offers hope of salvation, but in a fire, anyone would prefer to give a tree a wide berth. One may therefore well ask how any permanent and effective method can be created o avoiding rays that are invisible and in constant process of change. As there is no on single all-purpose answer to this problem, we can only say that it is possible to get rid of harmful rays - and that this is indeed so is borne out by the innumerable letters of thank received from many lands. This book is intended as a serious scientific work for radiesthologist, incidentally the first of its kind worldwide.