Everyone knows that Bartók's compositions were strongly influenced by his work with folk music. For over 70 years commentators have repeated the fact in one form or another. Bartok himself noted shortly before his death: ‘It is almost a truism that contemporary art music in Hungary has Eastern European folk music as its basis. However, there is much misunderstanding and misinterpretation with reference to the relation between our higher art music and our rural music’. That ‘misunderstanding and misinterpretation’ was not entirely the fault of scholars and critics. Bartók's numerous essays on the subject, written between 1911 and 1944, all too often provide the reader with generalities. Where he is specific it is most usually about thematic, or occasionally harmonic, derivations from folk sources. With the exception of portions of the ‘Harvard Lectures’ (1943), however, Bartók avoids any sustained account of how folk music influenced the modal and tonal structures of his compositions. Above all, he never explains the principles behind his characteristic pitch notations, particularly those double sharps and double flats so frequently found in his scores.