One of the great pleasures of looking through the online version of Music Fourth Year is finding images prepared for the volume that illustrate, or even encapsulate, the theory and sound that the Solesmes approach to chant was trying to achieve. In the image below we find sound, rhythm, and piety all pictured with loving care.
It is the most familiar Angus Dei, and the Solfege is represented here with numbers, with 5 being Sol, 6 as La, 4 as Fa, and so on. The lines show the musical phrase, imitated in the conducting style known as chironomy. One can see how the Mocquereau/Ward view of the use of the upbeat is employed in chant, so that every new phrase begins with upward motion. Isn't it beautiful?