Tetrachordon was published on March 4, 1645, the same day as Colasterion. (In the British Library's Thomason collection, the two tracts appear in sequence, Colasterion first, and both are clearly marked "March 4th" and "1644," which reflects the old style of counting years.) Both treatises undertake to defend Milton's Doctrine and Discipline of Divorce (DDD), published first in 1643 and again, in an expanded version, in 1644. Each is addressed, however, to a different audience and seeks to defend DDD against a different foe. In Colasterion, Milton took aim at the nameless author of An Answer to the Doctrine and Discipline of Divorce. There he indulged in ridicule and insult to make his points. Tetrachordon proceeds in quite different manner and style.

Tetrachordon is, like the DDD, addressed to Parliament, and was prompted by two different kinds of responses to his previous work. First Milton defends his work against the public (and published) attacks by two well-known clergymen, Daniel Featley and Herbert Palmer. Palmer, a member of the Westminster Assembly of Divines, preached a sermon to MPs assembled in St. Margaret's, Westminster for an "Extraordinary Day of Humiliation" held on August 13, 1644. His sermon was printed shortly thereafter as The Glasse of Gods Providence towards His Faithfull Ones. On page 57 of the printed sermon, Palmer refers to Milton's DDD as "a wicked booke" and "deserving to be burnt." Dr. Daniel Featley, in a pamphlet directed against Anabaptists called The Dippers Dipt (1645), lists Milton's DDD among a number of recent publications he considered impious and dangerous: "Witnesse a Tractate of Divorce, in which the bonds of marriage are let loose to inordinate lust, and putting away wives for many other causes besides that which our Saviour only approveth, namely, in case of Adultery" (sig. B2v). Milton addresses both of these attacks in his prefatory remarks, "To Parlament."

However, Milton's chief motivation for composing Tetrachordon was a good deal more positive. Some readers "more judicious" than Palmer and Featley thought DDD full of rational argument and wished "that the Scriptures there alleg'd might be discuss'd more fully." That is precisely what Milton undertakes by a painstakingly detailed exegesis of "the foure chief places in Scripture, which treat of Mariage, or nullities in Mariage." These "places" are found in Genesis 1 and 2, Deuteronomy 24, Matthew 5 and 19, and 1 Corinthians 7. His exegeses of these passages, claims Milton, demonstrate that these four places harmonize with each other in a consistent teaching about marriage and divorce—a four-part harmony or chord or tetrachord, as in the ancient Greek four-toned scale.

As in his DDD, Milton grounds his argument in what he calls the institution of marriage by God almost immediately following the creation of man, and coincident with the creation of woman. Indeed, he regards the creation of woman, as recorded in Genesis 2:18-24, as the record of the institution of marriage. All other passages of scripture Milton explicates in harmony with these words of institution in Genesis. Marriage, like the institution of the Sabbath, and all other gifts of God, was intended "for the good and comfort of man." This benefit is, in the first instance, gender-specific—to remedy the first man's loneliness, the only aspect of creation God found to be "not good" (Genesis 2:18). According to Milton's exegesis, God intended marriage for the following purposes, ranked in order of priority:

  1. mutual help to piety
  2. civil fellowship of love and amity
  3. generation of offspring
  4. household affairs
  5. remedy of incontinence
The first four of these can easily be understood as benefits to both men and women, but the remedies of loneliness and incontinence are here understood as specific to men. According to the canon laws of both the Roman Catholic and the English churches, divorce could only be granted for physical considerations (frigidity, adultery, barrenness); Milton follows continental reformers' teaching by prioritizing the non-physical aspects of marriage. At the risk of some oversimplification, then, the Mosaic laws concerning divorce must be understood, Milton argues, in the light of the words of "the prime institution" in Genesis. Even Adam's first pronouncement—"This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man. Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh" (Genesis 2:23-24)— must not be misunderstood as suggesting that marriage is principally a matter of fleshly union, any more than the eucharistic words, "This is my flesh" should be so understood. When it comes to Jesus's words in Matthew 5 and 19 apparently forbidding divorce except in cases of adultery, once again, we must not interpret them so literally as to find them out of harmony with the sense of the words of institution in Genesis. Therefore, Jesus cannot possibly mean to contradict either God's instituting words in Genesis or God's law as given to Moses and recorded in Deuteronomy. Finally, Paul's words in 1 Corinthians 7, insofar as they may be considered part of God's holy word rather than just Paul's personal advice, also should not be interpreted against the record of "institution" in Genesis.

Tetrachordon includes more than scripture exegesis. It also advances arguments about natural and civil law, claiming that marriage is not a natural, but a "civill and ordain'd relation." Therefore, although one cannot divorce a parent or a sibling because they are naturally related, a spouse is related only civilly. Milton acknowledges that Adam and Eve were, according to Genesis, more than civilly related, but, he concludes, "The rib of Mariage, to all since Adam, is a relation much rather then a bone" (my emphasis). The tract privileges scripture exegesis and logical argument over authoritative examples and testimonies; nevertheless, Milton concludes the treatise with an exhaustive list of testimonies in support of his arguments that includes:

Echoing his claim in Areopagitica that official censorship was a Roman Catholic innovation, Milton here charges that "the Popes Canon Law" was the first to encroach upon civil magistracy in outlawing divorce.

Three particularly thought-provoking recent articles on Tetrachordon and the divorce tracts are

Their notes and references are a reliable guide to earlier scholarship.

The copytext for this edition of Tetrachordon is the British Library's Thomason / 45:E.271[12] from Early English Books Online. Two pages, numbered 40-41, are missing from the EEBO version; they are not missing from the BL copy of the book; they probably were inadvertently skipped over when the the book was first photocopied for microfilm. This may well have been prompted by the misnumbering of pages in the 1645 printing where page 40 (signature F4v) is followed by 37-39, and then resumes at page 40 again (G2v). As a result, EEBO skips G2v and G3r. I have also consulted four other BL copies and the copy in Rauner Special Collections at Dartmouth College.