But sucked on country pleasures, childishly?
Or snorted we in the Seven Sleepers' den?
'Twas so; but this, all pleasures fancies be.
If ever any beauty I did see,
Which I desired, and got, 'twas but a dream of thee.
And now good-morrow to our waking souls,
Which watch not one another out of fear;
For love, all love of other sights controls,
And makes one little room an everywhere.
Let sea-discoverers to new worlds have gone,
Let maps to other, worlds on worlds have shown,
Let us possess one world, each hath one, and is one.
My face in thine eye, thine in mine appears,
And true plain hearts do in the faces rest;
Where can we find two better hemispheres,
Without sharp north, without declining west?
They see each other’s reflection in their eyes, demonstrating their reciprocal spiritual bonding. Eyes, of course, are said to be ‘windows of the soul’ 
 Donne encapsulates this cleverly and concisely,  with two balanced clauses, one mirroring the other, a device known as  chiasmus . Note also the internally rhyming ‘thine’, mine' and the  assonant  ‘eye’. There is a rhythmic harmony about this line that reflects the meaning. 
 Note that Donne incorporated spherical imagery such as eyes into many of his poems, as he viewed the sphere as a perfect shape.
The Good Morrow