How sweet and lovely dost thou make the shame
Which, like a canker in the fragrant rose,
Doth spot the beauty of thy budding name!
O! in what sweets dost thou thy sins enclose.
That tongue that tells the story of thy days,
Making lascivious comments on thy sport,
Cannot dispraise, but in a kind of praise;
Naming thy name blesses an ill report.
O! what a mansion have those vices got
Which for their habitation chose out thee,
Where beauty's veil doth cover every blot
And all things turns to fair that eyes can see!
Take heed, dear heart, of this large privilege;
The hardest knife ill-used doth lose his edge.
In a circular argument Shakespeare returns to the idea of the first three lines: the boy’s beauty transforms his rumoured bad deeds to fair ones. What’s visible is beautiful and anything that isn’t is made beautiful by the sheer overwhelming power of what he is. 
 The first three quatrains end with an exclamation mark and the  volta  forming a pause or  caesura . We know that Shakespeare will deliver a surprise or twist in the logic.
Sonnet 95