Transcutaneous

Weary with toil, I haste me to my bed,
The dear repose for limbs with travel tired;
But then begins a journey in my head
To work my mind, when body's work's expired:
For then my thoughts--from far where I abide--
Intend a zealous pilgrimage to thee,
And keep my drooping eyelids open wide,
Looking on darkness which the blind do see:
Save that my soul's imaginary sight
Presents thy shadow to my sightless view,
Which, like a jewel hung in ghastly night,
Makes black night beauteous, and her old face new.
Lo! thus, by day my limbs, by night my mind,
For thee, and for myself, no quiet find.




*Here the poet reflects on how thoughts of the beloved keep him awake, and even in darkness the image floats before him, like a jewel hung in ghastly night, making the face of night beautiful. Thus by day the poet is made weary by toil and travel, and by night rest is denied him, for he has to make journeys in his mind to attend on the loved one, who is far away.

Intend a zealous pilgrimage = start off on a journey.
To intend a journey, meaning to commence or undertake a journey, was common parlance, deriving ultimately from Latin iter intendere. Pilgrimages were undertaken by the faithful in Shakespeare's day as acts of devotion, involving long and tedious travelling, often on foot, or horseback, for several weeks, to visit some holy shrine. Chaucer's pilgrims in the Canterbury tales were on horseback, but their journey was to take many days. There is nothing which corresponds to the experience in today's world of easy travel, and for Shakespeare's contemporary readers a zealous pilgrimage was a work of devotion lasting several weeks or months.
zealous = earnest, passionate, devoted.




*For thee, and for myself - i.e. "for both of us, because we are two hearts in one. Also, my thoughts, in visiting you, must cause you too to be awake".