LAERTES
[…] but you must fear,
His greatness weighed, his will is not his own,
For he himself is subject to his birth.
He may not, as unvalued persons do,
Carve for himself; for on his choice depends
The safety and health of this whole state.
And therefore must his choice be circumscribed
Unto the voice and yielding of that body
Whereof he is the head.
(1.3.19-27)
Laertes tells Ophelia that Hamlet can't marry who he wants to—he has to marry for the "safety" of the entire "state." And he's right. If you were rich and powerful in the 16th century, your marriage was an opportunity to forge strategic political, social, and economic alliances. In other words, Laertes insists that a marriage between Ophelia and Hamlet is impossible. Marrying for love? That was for the commoners.
LAERTES
[…] Then if he says he loves
you,
It fits your wisdom so far to believe it
As he in his particular act and place
May give his saying deed, which is no further
Than the main voice of Denmark goes withal.
Then weigh what loss your honor may sustain
If with too credent ear you list his songs
Or lose your heart or your chaste treasure open
To his unmastered importunity.
(1.3.27-36)
Here, Laertes tells Ophelia that, if she sleeps with Hamlet, she'll lose her honor. But this isn't a moral argument on the ethics of premarital sex. He's talking about the way Ophelia's chances for a future marriage could be compromised—which is literally a matter of life or death for a young woman.
Quote 9
LAERTES
O, treble woe
Fall ten times treble on that cursèd head,
Whose wicked deed thy most ingenious sense
Deprived thee of!—Hold off the earth awhile,
Till I have caught her once more in mine arms.
(5.1.258-262)
Here, Laertes leaps into Ophelia's grave so he can hold "her once more in [his] arms." Oh, and this happens right before he fights with Ophelia's ex-boyfriend about who loves Ophelia the most. Traces of incestuous desire? Uh, yeah.