We are constantly reminded of the pervading atmosphere of decay through the imagery used in the play. It is a significant point that the ghost, the only character that could arguably be termed an outside observer, and who is certainly qualified to make some form of prophetic judgement, should be one of the prime sources of imagery of decay, poison and rotting.
Upon my secure hour thy uncle stole
With juice of cursed hebona in a vial,
And in the porches of my ears did pour
The leperous distilment . . .
. . . doth posset
And curd, like eager droppings into milk,
the thin and wholesome blood. So did it mine.
And a most instant tetter barked about,
Most lazar-like, with vile and loathsome crust
All my smooth body [Act I, Sc. v, 66 - 78]
A graphic description, especially since only moments before the ghost had instructed Hamlet not to pity it!
Throughout the play we can trace a progression of corruption, that leads to death, through 'disease' in the characters of Polonius, Claudius and Hamlet.
Polonius is perhaps the most obviously corrupt character in Hamlet. His corruption has occurred long before the play begins; the progression is in the extent to which it is revealed to us. From this...