Terry started a discussion about how Polonius' famous advice to his son could be played. This post will get into the trope of fatherly advice to a departing son that Shakespeare was referencing.
According to Harold Jenkins in his classic 2nd ed. Arden Hamlet (1982), the rhetorical tradition behind Polonius' advice begins with Isocrates in ancient Greece. Isocrates was a contemporary of Socrates and later a rival to Plato. He founded a school of rhetoric five years before Plato's Academy. Isocrates' influence on rhetoric was formative and profound.
Isocrates wrote a letter of advice on how to achieve moral and intellectual excellence that is now known by its Latin name Ad Demonicum. It was addressed to the son of Isocrates' friend Hipponicus after Hipponicus' death. It is far longer than Polonius' advice, and has 43 sections on subjects ranging from Duty toward Heaven, On the choice of friends, and On dress.
By Shakespeare's time there had been a long tradition of similar rhetorical pieces of advice given out to sons. Sir. Walter Raleigh wrote a book called Instructions to his Son and to Prosperity (1632) and the 9th Earl of Northumberland had his own Advice to his Son, the later written by Hary Percy while he was a prisoner in the Tower of London after his trial in the Star Chamber. In addition to these real examples, literature at the time had many more. Jenkins indicates Lyly's Euphesus, Green's The Card of Fancy, Florilo's Second Fruits, and most importantly Shakespeare himself in All's Well that End's Well (where the advice comes from a mother):
63: Be thou blest Bertrame, and succeed thy father
64: In manners as in shape: thy blood and vertue
65: Contend for Empire in thee, and thy goodnesse
66: Share with thy birth-right. Loue all, trust a few,
67: Doe wrong to none: be able for thine enemie
68: Rather in power then vse: and keepe thy friend
69: Vnder thy owne lifes key. Be checkt for silence,
70: But neuer tax'd for speech. What heauen more wil,
71: That thee may furnish, and my prayers plucke downe,
72: Fall on thy head. Farwell my Lord,
73: 'Tis an vnseason'd Courtier, good my Lord
74: Aduise him.
For a fuller discussion, see the extended notes in the Furness New Variorum Hamlet (1877). Note that while critical opinion often takes Hamlet's side and considers Polonius to be a prattling fool, Jenkins says:
"Such conventional precepts are entirely appropriate to Polonius as a man of experience. It is a mistake to suppose they are meant to make him seem ridiculous. Their purpose, far more important than any individual characterization, is to present him in his role of father. What is being dramatized in the advice as in the blessing is his son's departure from home and by impressing upon us here the relation between father and son the play is preparing for the emergence of Laertes later as the avenger who will claim Hamlet as his victim."