The book is a statement of the modern theory of aspects in astrology. The traditional and the newest approaches in classification of aspects, in definition of their properties are considered in detail. The dynamics of aspects through the development of their programs was studied. A structure is defined in which each aspect has its own specific place and well-defined properties. The method of aspects interpretation is given. The book contains a large reference material, which makes it possible for a deeper analysis of any aspect in the horoscope.