Consider doubling in this play. What events or characters are doubled? Is there an exact, mirror-image correspondence between the doubled items or occurrences, or is the second time/thing different than the first? What is the significance of doubling, considering these similarities and differences, in this play?
Some doubled events in this play include: the tempest that lands Pericles in Pentapolis and the one in which Thaisa dies; the failed attempt at murdering Pericles and at murdering Marina; the supposed death of Thaisa and Marina, both of whom are discovered to be alive. Most of those events happen twice but one is not greater or lesser, better or worse than another. They serve to multiply the events--though why was one not enough?
Other doubled events are bad in one occurrence and good in another, such as the contrast between the contest for the hand of the king's daughter in Antioch, an incest-corrupted land, and in Pentapolis, where both the king and his daughter are understood to be good people. The bad incestuous relationship between Antiochus and his daughter is contrasted with the good father-daughter relationship between Simonides and Thaisa, Pericles and Marina. Consider also the lively popular culture of the fishermen, contrasted with the degraded popular culture of the brothel.
These doublings show a certain kind of consistency in the world of the play. Things happen again and again, showing pattern. The key is to endure, in Pericles's case. That some things are the good double of a bad thing represents the doubled-edged sword of every event and relationship--in some cases good prevails and in others evil wins out.
What is the role of the sea in this play? Consider the tempests that beset Pericles, and how he internalizes the idea of the tempest when he believes Marina to be dead. Think also of the fishermen in Pentapolis and their common-sense wisdom about the sea. The sea serves as a link between all the nations in this play--what else does it do?
The sea is like another Gower-like force in the play--always present and influential to events of the play but never really mentioned by the characters themselves. The sea is many simple things: it's transportation between the many city-states; it's a place of danger, where tempests shipwreck Pericles and pirates kidnap Marina (though taking her to a fate that may be better than being murdered). Yet, as the fishermen note, it is also a place where the relations between various classes of men are played out in the fishy kingdom. The fishermen compare whales to misers, who drive all the smaller fish before them and then eat them up by the mouthful--just like great men devour lesser men on land. After so much time on the sea, Pericles himself starts to internalize the workings of the sea, and suffers an internal "tempest" when he hears of his daughter's alleged death. The sea becomes a metaphor for human life--where sufferings are felt as tempests, and great men (like Pericles) can succeed where smaller men (like the fishermen who help him get to the tournament where he wins the heart of Thaisa) remain in the background. In Shakespeare, the natural world often reflects the life of men, or serves as a metaphor for it; here the Mediterranean Ocean is both the location of Pericles's journey and the symbol of it.
Pericles is filled with kings and kingdoms. Consider Antioch, Tyre, Tarsus, Pentapolis, Ephesus and Mytilene--what kind of collective portrait of aristocratic rule are we presented with?
The political value of rule by aristocrats seems to be in doubt. Antioch is ruled by an incestuous king who apparently dies without a successor. Cleon of Tarsus has let his kingdom fall into famine, and his formerly proud people are cowed; later his wife becomes a murderer, and both are killed in an uprising, leaving an uncertain future for the kingdom. No king of Ephesus is introduced--instead Cerimon provides an image of charity that is supposed to stand for the kingdom. The governor of Mytilene goes to a brothel in disguise, and abandons his land to rule Tyre with Marina. When Pericles himself is suspected of abandoning Tyre, his lords want to crown Helicanus, who has the backbone to resist--but later he too leaves the kingdom to travel with Pericles. Simonides is the best example of a king who remains in his nation, but his death merely provides an opportunity to divide up the collective holdings and separate a newly reunited family. And his kingdom cannot have been all good, considering the analysis made by the fishermen.
On one hand this reflects a kind of absenteeism in governing that was actually prevalent in Shakespeare's time, under the leadership of James I. And it also may reflect the isolation of the contemporary ruling families of Europe, where royal brothers and sisters were married into various royal houses in distant nations.
On the other hand, it also shows that no kingdom is truly good. It's better to have an absent king, like in Tyre or Ephesus or Mytilene, than a bad king, like in Antioch or Tarsus. But certainly aristocratic rule is put into question when none of the many kings and governors who fill this play are capable of any coherent rule.