John Donne's "The Good-Morrow" is a classic love poem, likely written by the poet's wife, Ann Moore. The first two stanzas draw out the poet's love for this woman, proclaiming love itself as the all-important event in life.

The third stanza continues on a similar path, beginning with an image of the two lovers looking at each other proclaiming, "My face in thine eye, thine in mine appears". This line refers to the two lovers gazing closely at each other, seeing themselves in their lover's eyes. It can be considered on a literal or metaphorical level; eyes do offer literal reflections, and one can see oneself in another's eyes, but the metaphorical interpretation suggests that John and his love only see each other because they're so deeply in love.

"Where can we find two better hemispheres/without sharp north, without declining west?" Since a hemisphere is only half of a sphere (think of each hemisphere as being half of a globe), Donne is drawing a traditional yet poetic image of the two lovers only being half of the entire whole. Donne is not complete without his love, and she is not complete without him. 

The poem continues, "Whatever dies, was not mixed equally". Donne is explaining that true love cannot die, but that true love also requires reciprocal effort. Each lover needs to contribute equally, and only if the love is true can it never die.

The poem concludes, "If our two loves be one, or, thou and I/Love so alike, that none do slacken, none can die". With this final line, Donne continues the previous thought of eternal love and mutuality. If he and his lover are able to love each other truly, wholly, and equally, they can transcend mortal death. Their love is more powerful than all, and it cannot simply die. It's also interesting to note Donne's usage of the word "die" as the final word of the poem. In a literal sense, the poem ends at the word "die", just like a life is ended at death. Yet, the poem transcends time and escapes its death by existing as a form of love and art. Like the love described in the poem itself, "The Good-Morrow" is eternal.

What is the analysis of the third stanza of "The Good-Morrow"?

In the third and final stanza of "The Good Morrow," the speaker develops the geographical metaphor set out in the previous stanza. There, he was more than happy to leave the crossing of the oceans and the exploration of new worlds to others. The only world he was interested in was the world he shares with his beloved.

And in that world, the love between the speaker and his beloved is strong: so strong, in fact, that the truth of their love can even be seen in each other's faces:

My face in thine eye, thine in mine appears,
And true plain hearts do in the faces rest.

These lines reinforce the sense that the two lovers are in their own little world, entirely self-contained and without any need to explore any other worlds. The speaker takes up the geographical metaphor again when he refers to himself and his lover as two hemispheres. The implication is that they fit together perfectly to form one world: a world which, unlike the Earth, doesn't contain a frozen north or the darkness that follows the setting sun. There is no cold or darkness in this relationship.

Their love is such that it can never perish. This is because, according to the speaker, only that which isn't mixed together equally can do so. But as these lovers, these two hemispheres, are indeed equal halves of a perfect whole, the love they share can never die.