Prof. John Satterly's introduction for the song "hv":

Times change. The quantum comes on the scene and the laws of radiation are clarified by Planck and his successors. The wave theory, however, still holds the field in its beautiful explanation of interference of light and diffraction effects. The two rival theories seem inconsistent yet both are necessary; as Sir William Bragg said “We teach the wave theory on Mondays, Wednesdays and Fridays and the quantum theory on Tuesdays, Thursdays and Saturdays.” The author of this song is G. Stead, a Cambridge graduate, teacher and author of a well-known textbook on general physics.