What Robert Pelletier does in Planets in Houses has never been done before in the history of astrology. He discusses the meaning of each planet in each house as derived by counting from each of the other eleven houses, and he discusses the meaning of each house position in relation to the other houses with which it forms trines, sextiles, squares and oppositions, inconjuncts and semi-sextiles. In each chapter, wheel symbols graphically show the seventeen different house relationships delineated for each planet. Finally, Pelletier delineates the Sun-Moon polarities in terms of the wheel of houses: for each house position of the Sun, he interprets each of the twelve possible related house positions of the Moon. Each chapter presents the traditional meaning of the house and explains how the derivative house system applies to it.