Sonnets 18, 19, 20, 21, and 23 were numbered XV., XVI., XVII., XVIII., and XIX., respectively in Poems (1673).

Introduction. As many have noted, Sonnets 20 and 21 form a complementary pair of lyrics ( see Lewalski's Life of John Milton 354). Sonnet 20 praises Henry Lawrence and 21 praises Cyriack Skinner in tones reminiscent of Martial and Horace. Both appear to have been written in 1655 or 1656 when the most puritanical of the major-generals advising Cromwell's government urged the repression of sports and recreations they regarded as unsuitable for truly reformed Christians. Richard Baxter, in a number of sermons preached and printed during these years, railed against "needless sports" and "recreation" as all one with cards, dice, drunkeness and ungodly behavior in general. He also regarded the persistence of parish sports and recreations as a dangerous throw-back to the Laudian church under Charles I:

And now Hearers, what is your resolution? perhaps you have been enemies to Christ under the name of Christians: Will you be so still? Have you not loathed this busie diligent serving of him? and hated them that most carefully seek him, more then the vilest drunkard or blaspemer? Have not his word and service and sabbaths been a burthen to you? Have not multitudes ventured their lives against his Ordinances and Government? Nay is it not almost the common voice of the Nation in effect, Give us our sports and liberty of sinning, give us our Readers, and singing-men, and drunken Preachers, give us our Holy-daies and Ceremonies, and the Customes of our fore-fathers; Away with these precise fellows, they are an eye-sore to us; these precise Preachers shall no Single illegible letter controll us, this precise Scripture shall be no Law to us, and consequently this Christ shall not Rule over us. (Three Treatises to awaken secure sinners London 1656, 120-21)

Milton regarded recreation quite differently; see Tetrachordon, Of Education and The Reason of Church Government.

Sonnet 21 spends a quatrain praising his friend's famous grandfather, Sir Edward Coke in much the same way Horace praised his addressees by way of their ancestors (see Horace, Odes, Poem 1). The rest of the poem invites the addressee to set aside intellectual pursuits for a "cheerful hour" or even a day of mirth. The speaker counsels proper measures of work and relaxation.

Sonnet 21. All but the first four lines of this sonnet appear on a sheet of the Trinity MS along with Sonnet 22.

Cyriack. Cyriack Skinner was the grandson of Sir Edward Coke, who served as Chief Justice of Common Pleas and the King's Bench from 1613-16 and authored the famous The Institutes of the Law of England. He served Milton as a reader and amanuensis.

Themis. Goddess of justice.

Let Euclid rest. Cyriack Skinner may have learned about ancient mathematicians while a pupil at Milton's school on Aldersgate Street.

what the Swede intend. Cyriack Skinner's study of international politics may have lead to an interest in the campaign against the Poles conducted by Charles X of Sweden in 1655. The poem echoes Horace's Odes 2.11.1-6 and 3.8.17, in which the speaker tells his friend to choose recreation over study, because youth is too fleeting not to have fun.

Heav'n a time ordains. In Ecclesiastes 3:1 states "To every thing there is a season."