Explanation:
This poem is one of Marvell's most emblematic poems, reminiscent at times of Vaughan's The Water-fall. The dewdrop becomes a symbol of the human soul, just as in Vaughan's poem, the spray from the waterfall become a sign of the return of the soul to heaven. The same Platonic thought is present in Marvell. Probably the mid-seventeenth century, when both these poems were written, was the time when Christian Platonism had its greatest influence. You can look at this more fully in the analysis of Marvell's The Garden.
Description of the dewdrop
Lines 1-18 describe the dewdrop itself; the remainder of the poem works out the symbolism in terms of the soul's returning to heaven. The dew is ‘orient', that is, from the East, because that is the direction of the dawn. Marvell's point is that, however beautiful its resting place, ‘the blowing Roses', it still stays minimally attached to it (‘scarce touching where it lyes'). Its moisture is a sign of weeping (‘Like its own Tear') because it is ‘so long divided from the Sphear', that is, the sky or the heavens. It is just not in its element on earth, only in the air. Finally the sun takes pity on it and draws it back through evaporation.
Emblem of the human soul
This is an emblem or sign of the human soul, which stems originally from ‘the clear Fountain of Eternal Day', that is, heaven itself. This is also Vaughan's belief, as in Platonism in general, that the soul comes from heaven, and longs to return to it. Orthodox Christian theology does not teach anything about the origin of the soul, so such a belief is pushing at the bounds of Christian belief, without being against it.
A microcosm
‘Remembering still' – this is the source of its sadness, since it remembers loss. But it tries to re-create heaven in preserving its own purity. The drop formation of the dew is again a sign of this: it turns in on itself, trying to absorb as little as possible of the material world. So it becomes a microcosm, ‘The greater heaven in an heaven less', except ‘cosm' derives from ‘cosmos', which means universe, rather than heaven. The reflective language which Marvell uses of the dew-drop - 'Like its own tear' - is a linguistic enactment of the soul shrinking away from involvement in the world.
The other emblematic feature of a drop is that it is transparent and can absorb light as the soul does. And just as the dewdrop is ready to evaporate as soon as possible, so is the soul.
Like manna
The final image is biblical, that of manna, the ‘food from heaven' given by God to feed the Israelites, as recorded in Exodus 16:14-15. The poet has to modify the image considerably, since on his own admission, the flakes of manna turned ‘congeal'd and chill', not an appetising picture! However, it fell like dew and what was not needed, dissolved, evaporated back to heaven.
The verse form is moving towards free verse, though there are loose rhyming patterns. The metre varies between pentameter and tetrameter, with trochees almost as prevalent as iambs.