Not from the stars do I my judgement pluck;
And yet methinks I have Astronomy,
But not to tell of good or evil luck,
Of plagues, of dearths, or seasons' quality;
Nor can I fortune to brief minutes tell,
Pointing to each his thunder, rain and wind,
Or say with princes if it shall go well
By oft predict that I in heaven find:
But from thine eyes my knowledge I derive,
And, constant stars, in them I read such art
As truth and beauty shall together thrive,
If from thyself, to store thou wouldst convert;
Or else of thee this I prognosticate:
Thy end is truth's and beauty's doom and date.
Doesn't get his knowledge from the stars, but he has astrological knowledge anyway. He's getting the knowledge from his lovers eyes. (Dearth- lack of, little, famish). Doesn't use his knowledge to tell the future, not an advisor to the King or Queen.
Uses his lovers eyes as a constant start, something that he can always follow, like a navigator. If she doesn't have kids, truth and beauty will be gone, sleep with me or beauty will be lost.
When I consider every thing that grows
Holds in perfection but a little moment,
That this huge stage presenteth nought but shows
Whereon the stars in secret influence comment;
When I perceive that men as plants increase,
Cheered and checked even by the self-same sky,
Vaunt in their youthful sap, at height decrease,
And wear their brave state out of memory;
Then the conceit of this inconstant stay
Sets you most rich in youth before my sight,
Where wasteful Time debateth with decay
To change your day of youth to sullied night,
And all in war with Time for love of you,
As he takes from...