During the eighth, twelfth, and fourteenth centuries, strife raged between the presiding prelates of the church, the nobility, and the religious orders in Europe. A great many of the religious men and women of the time suffered, particularly in Rhineland.

There, strife between Pope John XXII and Louis of Bavaria caused the Pope to place Louis’ dominions under and interdict. The interdict allowed the Pope to restrict public worship and forced the removal of all rites of the church, other than baptism and extreme unction, from all those who were faithful to Louis.

In response, a group of men and women who desired to show that the life which Christ promised could be lived in the midst of chaos joined together in a secret group in order to maintain the life and order of the church. They kept the precepts of the church, taking the name "The Friends of God." Their association extended throughout the province of Rhine, including towns such as Strassburg and Nuremberg.

This group created the doctrines that would be their rule for their daily life. These doctrines included: (1) the complete giving up of self-will to the will of God; (2) the continuous activity of the spirit of God in all believers; (3) the worthlessness of all religious activity based on fear or the hope of gain; (4) the essential quality of laity and clergy.

One of the greatest works that emerged from this mystical group was the Imitation of Christ, written by stalwart member Thomas a’Kempis.

Other scholars that emerged from this group were Meister Eckhart and Gerhard Groote. All of these religious geniuses made significant contributions to debates of the day, continuing to bind together under the rule of the Friends of God, which later became known as the Brethren of the Common Life.

The first community of the Brethren of the Common Life was formed at Deventer, followed by the rapid spreading of the movement throughout Holland and Germany. Brother houses and sister houses were developed. Members of the group took no permanent vows, but mingled in the world for the purpose of service. Their garb was gray to reflect the simplicity of their life, while living strictly by the labor of their hands. Their emphasis was on the practice of the spiritual life and service to the community.

The chapel window displays the group’s general characteristics. A shield showing the Holy Spirit radiates four flames, symbolic of the awakening of the whole geographical region that was influenced by the Friends of God. The circle represents the Rhine River, surrounding the "Green Isle," where Dominican cloisters maintained the sacred activities of the Friends. The inscription, "The Brethren of the Common Life" refers to the movement which developed out of the founding group. A preacher is depicted on the window, telling the doctrines of inner life, a theme tying this group to the Quakers, who are represented in the eighth window honoring John Woolman.