Why Does Polonius Send Reynaldo To Paris?

In Act 1 Scene 2 of Hamlet, Polonius sends his servat, Reynaldo, to Paris to keep an eye on his son, Laertes. In a dialogue with a servant, the petty, vain, selfish nature of Polonius is revealed, as he does not even trust his own son.
Polonius urges Reynaldo to lie about Laertes. He wants Reynaldo to spread bad rumors about Laertes, but to make sure he is saying it in a way he “can gather information and in a way that it doesn’t seem so bad, nothing to do with sexual activity just to see what he has been doing”. He instructs Reynaldo, “Your draw of lie takes this carp of truth; And subsequently do we of astuteness and reach, With windlasses and with examines of inclination, By indirections discover headings out.”
Polonius is very controlling father so he plans this manipulation in hopes to find out what Laertes is actually doing while in Paris.