During the refounding of the Anthroposophical Society as the General Anthroposophical Society at Christmas 1923/24, Rudolf Steiner also reconstituted, as the School of Spiritual Science, the Esoteric School he had led in three classes from 1904 to 1914, at the same time extending its scope by adding artistic and scientific Sections. However, owing to his illness and later death in March 1925, he was only able to make a beginning by establishing the First Class and the Sections. The actual step from the Esoteric School to the School of Spiritual Science was nevertheless an exceptional one. The Esoteric School from Helena Blavatsky's time had been secret. Its existence was known only to those personally invited to participate. In contrast, the existence of the School of Spiritual Science was stated openly in the public statutes of the General Anthroposophical Society. From the Christmas Conference onwards, Rudolf Steiner worked within this publicly acknowledged framework. The Class Lessons comprise a complete spiritual course of nineteen fundamental lessons given between February and August 1924, several lessons given at other locations, and seven further lessons from September 1924 which take up the themes of the first part of the nineteen lessons in a modified form. This authentic, accurate and high-quality bilingual edition - with English and German texts printed side by side - is published in conjunction with the School of Spiritual Science at the Goetheanum. A compact four-volume clothbound set, it features plates with Rudolf Steiner's handwritten notes of the mantras and reproductions of his original colour blackboard drawings. The translations of the mantric verses have been reworked by a committed group of translators, linguists and editors, expressing subtleties of meaning, grammatical accuracy and poetic style whilst retaining the original sound and metre of the German mantric forms. Three versions of the existing English translations are also included.