Analysis of The Scrutinie. Song

I.
Why shouldst thou sweare I am forsworn,
  Since thine I vow'd to be?
Lady, it is already Morn,
  And 'twas last night I swore to thee
  That fond impossibility.

II.
Have I not lov'd thee much and long,
  A tedious twelve moneths space?
I should all other beauties wrong,
  And rob thee of a new imbrace;
  Should I still dote upon thy face.

III.
Not but all joy in thy browne haire
  In others may be found;
But I must search the black and faire,
  Like skilfulle minerallists that sound
  For treasure in un-plow'd-up ground.

IV.
Then if, when I have lov'd my round,
  Thou prov'st the pleasant she;
With spoyles of meaner beauties crown'd,
  I laden will returne to thee,
  Ev'n sated with varietie.