I tune the instrument here at the door,
And what I must do then, think here before.

To recognize its beauty, leaving aside the depth and truth of the phrase,
"Where I shall be made thy music," we must recall the custom of those
days to send out for "a noise of musicians." Hence he imagines that he
has been summoned as one of a band already gone in to play before the
king of "The High Countries:" he is now at the door, where he is
listening to catch the tone, that he may have his instrument tuned and
ready before he enters. But with what a jar the next stanza breaks on
heart, mind, and ear!

Whilst my physicians by their love are grown
Cosmographers, and I[72] their map, who lie
Flat on this bed, that by them may be shown
That this is my south-west discovery,
_Per fretum febris_--by these straits to die;--

Here, in the midst of comparing himself to a map, and his physicians to
cosmographers consulting the map, he changes without warning into a
navigator whom they are trying to follow upon the map as he passes
through certain straits--namely, those of the fever--towards his
south-west discovery, Death. Grotesque as this is, the absurdity deepens
in the end of the next stanza by a return to the former idea. He is
alternately a map and a man sailing on the map of himself. But the first
half of the stanza is lovely: my reader must remember that the region of
the West was at that time the Land of Promise to England.

I joy that in these straits I see my West;
For though those currents yield return to none,