Although Pope John XXII had extended the Feast of the Trinity to the Universal Church in 1334, Jean Colombe did not choose to illustrate the beginning of its office with a representation of the Three Persons.
Instead, he showed Christ in a church with stained-glass windows representing large figures, blessing with His right hand and holding the globe with a cross in His left hand. His arched brow, flowing hair, and double pointed beard conform to the fashion of the day.
The large B which marks the beginnings of the introit of the Mass for the Trinity also dates from the time of Jean Colombe.

small image (20KB) --- large image (182KB) --- Christ blessing the world (large) (199KB) --- Initial letters (large) (227KB)