to good advice be true

A couple of days ago I thought of Hamlet for some reason; my favorite of Shakespeare's plays, and the one with which I'm most familiar. Then I thought of Polonius - I've seen two versions, only. The one with Derek Jacobi about 25 years ago on TV, and one that Kevin Kline did in modern dress - also on TV. Both were excellent, except for the fellow who played Polonius in the second one. 

He played him as if he were an old fool, with advice not worth listening to. I realize that actors want to do something different with their character, but I didn't buy it.

Laertes, the son of Polonius (and Ophelia's brother, by the way), is going away on official business, and his father wants to give him some parting advice.

"Give thy thoughts no tongue, nor any unproportion'd thought his act.
 Be thou familiar, but by no means vulgar. The friends thou hast, and their adoption tried, grapple them to thy soul with hoops of steel, but do not dull thy palm with entertainment of each new-hatch'd, unfledg'd comrade.
Beware of entrance to a quarrel; but, being in, bear't that the opposed may beware of thee.
Give every man thine ear, but few thy voice. Take each man's censure, but reserve thy judgment.
Costly thy habit as thy purse can buy, but not express'd in fancy; rich, not gaudy; for the apparel oft proclaims the man; and they in France of the best rank and station are most select and generous chief in that.
Neither a borrower nor a lender be: for loan oft loses both itself and friend; and borrowing dulls the edge of husbandry.
This above all, - to thine ownself be true; and it must follow, as the night the day, thou canst not then be false to any man."

Foolish advice, indeed!