Jean Langlais was approached to write a music book containing pieces in that were relatively easy for use in both catholic and protestant church services. He agreed and wrote 15 works. He chose his student, Naji Hakim to also write 15 works.
Langlais' works are relatively easy and characteristic of his style. Someone should have told Hakim about the need to be playable...
The pieces were designed to lead into the next, allowing an organist to play for as long or as short as needed. They were written "in an impressionistic/twentieth century harmonic style" (Publisher's forward).