Who is it that sayes most, which can say more
Then this rich praise, that you alone, are you,
In whose confine immured is the store,
Which should example where your equall grew?
Leane penurie within that Pen doth dwell,
That to his subject lends not some small glory,
But he that writes of you, if he can tell,
That you are you, so dignifies his story.
Let him but coppy what in you is writ,
Not making worse what nature made so cleere,
And such a counter-part shall fame his wit,
Making his stile admired every where.
You to your beautious blessings adde a curse,
Being fond on praise, which makes your praises worse.
Changes to the original text: end of line 1, comma deleted; end of line 4, comma changed to question mark.
The first quatrain questions how it is possible that any poet might praise the young man more than simply to say 'you are you'. The pattern of who the young man is, is immured in his own breast, so there is no way of knowing what that pattern looks like in order to describe it or to find another such as he (the beloved).
The second quatrain repeats the 'you are you' formula. This is the most a poet can say, the highest praise he can give.
The third quatrain observes that if a poet should simply copy what is 'writ' in the young man's breast, that would assure his fame and his style would be admired everywhere. 'Counter-part' refers to the copy the poet has made.
The final couplet admits a fault in the young man: his liking of praise which, of course, redoubles the praise he gets.