As Jim’s place of exile, Patusan represents a retreat from white Western so-called civilization. Similar antagonisms exist here on a smaller scale, but it is with the arrival of Brown and his men that Jim’s idyll is shattered.
Through the depiction of Patusan and the later downfall of Jim, one may see that this isolated area symbolizes the poisonous effect of western civilization as represented by Brown. It also invites the readers to ask if it is ever possible to escape from the past as Jim continues to be haunted by his past despite living in this most isolated of places (isolated from the West, that is).
In order to help Jim in his acceptance into Patusan society, Stein gives him his silver ring. Doramin had given Stein this as a parting gift years before and, therefore, symbolizes trust and friendship. It is implied that Doramin gave this as a form of gratitude too as Stein ‘accidentally’ saved his life.
Jim gives the same ring to Dain Waris (via Tamb’ Itam) as an act of faith that Brown and his men should be allowed to leave by the river peacefully. This promise is broken by Brown and, consequently, the ring now stands for betrayal. When Doramin is given the ring (taken from Dain Waris’s dead hand), he shoots Jim in return.
Jim’s decision to jump from the sinking ship (the Patna) haunts him for the rest of his life. He tortures himself with what he sees as an act of cowardice and so it comes to represent his perceived lack of heroism.
It also personifies the dangers of the sea and highlights the ineffectuality of man when opposed to nature. This, in turn, exemplifies the inflated egoism of Jim and his feelings of shame as he would never have been able to stop the ship from sinking or save the 800 people on board anyway.