In his autobiography ‘The Course of My Life,’ Rudolf Steiner describes how at the turn of the century he was requested to hold theosophical lectures for what at that time was a very small theosophical circle in Berlin. He said he was willing to do so, but emphasised that he would only be able to speak about what lived within him as Spiritual Science. His first course of lectures given during the winter of 1900/01 was published at the request of the circle, compressed into book form, under the title ‘Mysticism at the Dawn of the Modern Age’. Because the results of his own spiritual knowledge contained within it were accepted in the General Theosophical Society, there was no longer any reason to refrain from bringing this spiritual knowledge in my own way before the theosophical public, which was at that time the only one which entered eagerly into these spiritual matters. I was not bound by any sectarian dogmatism; I remained someone who spoke out freely what he believed himself able to speak out entirely in accordance with what he himself experienced as the world of spirit.
During the next winter 1901/02 there followed a second series of lectures which was published in the summer of 1902 in book-form as Christianity as Mystical Fact. Immediately afterwards the German Section of the Theosophical Society was founded with Rudolf Steiner as General Secretary. Here I was able to unfold my anthroposophical activity before an ever-increasing public. Nobody remained in any doubt about the fact that in the Theosophical Society I would only bring forward the results of what I beheld in my own spiritual research.
This was the beginning of an ever-increasingly intensive activity in the sphere of spiritual-scientific lectures. In June 1903 appeared the first number of Lucifer (later Lucifer-Gnosis), Magazine for Soul-life and Spiritual-culture Theosophy. In the Spring of 1904 appeared the fundamental work Theosophy An introduction to Supersensible World-Knowledge and Human Destiny. There immediately followed in Lucifer the description of the path of schooling in the articles, How to attain Knowledge of the Higher Worlds and the presentation of a spiritual-scientific cosmology in the articles, From the Akasha Chronicle. (In English Cosmic Memory.)
Thus the German Section of the Theosophical Society was gradually built up by Rudolf Steiner and his closest coworker Marie von Sivers, later Marie Steiner, into a far-reaching, Central European, spiritual-scientific movement. From the beginning it was this anthroposophical teaching represented by Rudolf Steiner which later, owing to internal difficulties, took on independent existence as the Anthroposophical Society.
At the time when Rudolf Steiner gave the lecture-course entitled Foundations of Esotericism now for the first time appearing in book-form, the work was still in the initial stage of its development. Rudolf Steiner therefore always still made use of the expressions theosophy and theosophical and for the description of planetary evolution, of the members of man's being and so on, the Indian terminology usual in theosophical literature, to which at that time his audiences were accustomed. He makes special mention of the value of this terminology in the 15th lecture of this course. In his articles at that time and in his book, Theosophy he nevertheless makes use of expressions about which in 1903 he said in the magazine Lucifer, that for certain reasons he borrowed these expressions from an occult language which, in its terminology, deviates slightly from that in the published theosophical writings, but with which in essence it is naturally in complete agreement. Later he replaced these theosophical expressions ever more and note by those adapted to our European culture. The explanations necessary for this course are to be found at the end of the volume.
In the lectures the frequently recurring use of names taken from the writings of H.P. Blavatsky is to be explained by the fact that the audiences at this time were intensively occupied with the teachings of the founder of the Theosophical Society and, because of the difficulty of understanding their meaning, they often brought their questions to Rudolf Steiner. So again and again he explained Blavatsky's indications from her principal work The Secret Doctrine, in particular those in the third volume dealing with esotericism.
The entire course was in fact private verbal instruction, thus not intended for the general circle of members, but only for a few active members who were personally invited to take part. It was intended to provide a certain basis for their own group work. For this reason there is no complete shorthand report, but only notes which certain of his hearers made for their personal use. These notes have a strongly aphoristic character which should be borne in mind if, owing to their shortened and condensed content, or also as a result of gaps in the text, they are not always entirely comprehensible. If today these notes appear in the Complete Edition it is because on the whole they are certainly reliable, and also because they provide us with valuable aspects of human and cosmic considerations, which are not to be found in this form in Rudolf Steiner's later lectures. For the clarification and further understanding of many points, particularly those of a cosmological character, one should refer to the words written at about the same time, i.e. Cosmic Memory and Theosophy.