ENOn the basis of an unknown manuscript of the prominent Lithuanian conductor and pedagogue Saulius Sondeckis (1928-2016) Three Levels of a System, the paper analyzes certain fundamental and continuously relevant questions of musical education: questions of consistency, specialization, complexity and multi-level nature of the process of preparation of a professional musician; the correct assessment of a musicianís musical abilities; and the selection of a musicianís future artistic and professional path. The issues raised in the manuscript are formulated and addressed in the context of Sondeckisís personal teaching experience. A review of the indicated questions allows for a deeper understanding of the artistic legacy of Sondeckis and the principles of his teaching. Keywords: Saulius Sondeckis; the conductorís art; professional training of an orchestra musician.