According to Kessel’s book, Kersten used his power over Himmler’s abdominal cramps to act as a spy for the Swedish, Finnish, and Dutch governments in exile and to get him to abandon his plan to deport the whole population of the Netherlands to Poland. He told Himmler that his cramps would not yield even to his treatment while he, Himmler, was trying both to increase the size of the SS to more than one million members and work on the planned deportation; it was too much for his nervous system. Kersten told Himmler that he had to abandon one or the other if the massage to relieve his symptoms was to work; and he knew that increasing the size of the SS was more important. Himmler did abandon the plan to deport all the Dutch. However, no proof that such a plan existed has ever been found.
In the BMJ Dalrymple introduces Joseph Kessel’s The Magic Touch, a book about Heinrich Himmler’s personal doctor, Felix Kersten: