French musicologist and composer, Jacques Chailley (1910-1999) was born into a musical family and went on to study at the Paris Conservatoire. As an organist himself, he is well acquainted with the Chorales, making his analysis book J. S. Bach's Chorales for Organ well-informed. Bach's chorale catalogue consists of some 189 chorales; SATB hymns which tend to be in strophic form. Chailley's J. S. Bach's Chorales for Organ analyses the harmonic techniques, structure and other characteristics of all the chorales, including detailed descriptions. For all musicians, the knowledge of the harmonisation of Bach's chorales is essential. Therefore, Chailley's J. S. Bach's Chorales for Organ is imperative.