For the first week of the summer retreat at Dechen's European center, Lama Jampa Thaye will be teaching one of the most important Sakya teachings about vajrayana. Composed by the second of the five great Sakya Masters, Sonam Tsemo, this work is an extensive explanation of the nature and characteristics of the different categories of tantra as well as of the relationship between the tantras and the sutras.   As such it is an encyclopaedic resource for the study of the tantric system.  The text constitutes one of the major works studied in the Sakya shedra (college of studies) within the Dechen Community.