Explain the third stanza of Donne's "A Valediction: Forbidding Mourning"?

Question

This is the third stanza of John Donne's "A Valediction: Forbidding Mourning":

Moving of th' earth brings harms and fears,
Men reckon what it did, and meant;
But trepidation of the spheres,
Though greater far, is innocent.

What does this mean?

Answer 1

The difficulty here is ‘trepidation of the spheres’, so let’s start with a look in the dictionary:

sphere, n. 2. a. One or other of the concentric, transparent, hollow globes imagined by the older astronomers as revolving round the earth and respectively carrying with them the several heavenly bodies (moon, sun, planets, and fixed stars). The number of these was originally supposed to be eight, subsequently increased to nine and finally to ten by the addition of the ‘primum mobile’ and the ‘crystalline sphere’.

trepidation, n. 3. a. Astronomy. A libration of the eighth (or ninth) sphere, added to the system of Ptolemy by the Arab astronomer Thabet ben Korrah, c. 950, in order to account for certain phenomena, esp. precession, really due to motion of the earth's axis.

_{Oxford English Dictionary}

(See also Wikipedia’s ‘trepidation’ article.)

So the ‘trepidation of the spheres’ is a supposed libration (oscillation) in the direction or rate of the precession of the equinoxes, attributed to the imaginary ‘spheres’ of the heavens.

With this in mind we can interpret the stanza as follows. Since ‘trepidation of the sphere’ is a kind of vibration or quaking, the parallel phrase ‘Moving of th’earth’ must be an earthquake. An earthquake certainly ‘brings harms and fears’; its victims must count the cost (‘reckon what it did’); and since ancient times people have considered earthquakes to be portents, omens, or visitations of divine displeasure, and tried to work out what they ‘meant’:

it has often happened that […] earthquakes have predicted, with terrible truth, many of the evils which have befallen our own republic and other states.

_{Marcus Tullius Cicero (44 BCE). On Divination 1.18. Translated by C. D. Yonge (1853).}

The poet compares the movement of the earth to the trepidation of the heavenly spheres and points out that the latter is ‘far greater’, but is quite ‘innocent’ of harm: indeed, its effects can only be made out by the most learned of astronomers.

That’s the literal meaning of the stanza. But why has the poet chosen to write about earthquakes and astronomical events? The context of the whole poem is that the speaker is parting from their beloved, and is trying to persuade them not to cry or mourn: a ‘valediction’ being ‘An utterance, discourse, etc., made at (or by way of) leave-taking or bidding farewell’ (OED). The speaker attempts this persuasion through a series of increasingly outlandish metaphors. (The use of extended and ingenious metaphors, so-called ‘metaphysical conceits’, was a common feature of English poetry in the early 17th century when Donne was writing.)

Thus, in the first stanza the parting of the speaker and the addressee is compared to the death of a ‘virtuous man’, who dies so ‘mildly’ that his friends at the bed-side cannot make out which is his last breath. In the second stanza their parting is compared to the melting of ice, which ‘makes no noise’, unlike other partings which are accompanied by ‘floods of tears’ and ‘tempests of sighs’. So by the time we get to the third stanza we are primed to interpret it as another metaphor for how couples handle a separation. So the metaphorical meaning of this stanza is that the parting of an ordinary pair of lovers is like an earthquake: harmful, fearful, and dramatic; but the parting of the speaker and the addressee is like the trepidation of the spheres: ‘greater far’ because of the magnitude of their love, yet as calm and ‘innocent’ as the motion of the heavens.