There is not much to say about this little gem from the June 1932 CTM by P.E. Kretzmann besides to commend its clarity. Kretzmann succinctly summarizes, and gives the pertinent biblical citations for, the traditional Lutheran (biblical) teaching on marriage, divorce, and engagement.
Since the 1950's, the Missouri Synod has sounded an unclear note, or at least one inconsistent with its own history, concerning its teaching on what makes a marriage a marriage, particularly in regards to how one rightly enters into marriage.
Much of the confusion, or avoidance of the issue, arose from a desire during the mid-20th century to change the Synod's teaching on engagement--resulting in a weakened definition and understanding of marriage.
This is especially apparent when you trace the evolution of the synodical explanation of the catechism on the 6th Commandment. Up to and including the 1943 version, the teaching on the nature of marriage, and how it is entered into, reflects the same teaching that had been clearly set forth in countless articles, essays, books, and presentations throughout the Synod's history, which in turn stood in continuity with the teaching of Luther, Lutheran Orthodoxy, and the Scriptures themselves.
From the 1912 explanation: