[K:NWTS 23/3 (Dec 2008) 12]
As we may lawfully sing Scripture-psalms, so also songs and psalms of our own inditing (say some) agreeable to Scripture: “Sing unto the Lord a new song” framed on a fresh occasion. Therefore [in] 1 Cor. 14:26, a psalm is named among those things which they had for the use of the church. For seeing a psalm is but a musical prayer for the most part, therefore we may make songs for ourselves agreeable to the Word of God as well as prayers. And God knowing the efficacy of poetry and music to help [the] memory and stir up affection, allows his people to use it for their spiritual as well as natural comfort. The apostle speaks of “psalms, hymns and spiritual songs” (Eph. 5:19 and Col. 3:16). Who can show any reason to limit his speech to Scripture-psalms? Why may one not praise God in song for our deliverance in 88 or the Gunpowder treason?
 Edward Leigh (pronounced “Lee”) (1602-1671) was an English Puritan who served in Parliament (1636) and was a colonel in the Parliamentary army during the “War of the Three Kingdoms” (English Civil War, 1642-1651), until his expulsion from Parliament with others of the Presbyterian faction in 1648 (Pride’s Purge). He was the author of several important theological works, the most famous being his dictionary of Old Testament Hebrew and New Testament Greek (Critica Sacra, 1639-1644). The quotation above is from the second edition of A Systeme or Body of Divinitie (1654/1662) 841 (spelling and punctuation slightly modernized). Leigh’s reference to 1588 is to the destruction of the Spanish Armada by Sir Francis Drake. The Gunpowder Plot (1605) was a (failed) attempt by Roman Catholics to assassinate King James I.
Worship song books with more than Psalms were known from the Reformation period. For example, Kenneth H. Marcus cites the Constance Hymnal of Basel, Switzerland of 1559 which contained 235 songs, divided with 150 on the Psalms and 85 “Hymns” by other writers (“Hymnody and Hymnals in Basel, 1526-1606.” Sixteenth Century Journal 32/3  732).