Hamlet feels marooned in a situation which he is struggling to tolerate. This leads him to fantasise of methods of escape. The first of which (“O, that this too solid flesh would melt/ Thaw and resolve itself into a dew”) is the most metaphorical musing. It carries the contrast of concreteness (solid) to that of fluidity (dissolve and dew), which mirrors the conflict between the restriction of his current situation versus the freedom he desires. A pathos with the claustrophobia of Hamlet’s situation is generated largely out of the hopelessly abstract quality of his wish.
The next musing in the list (“Or that the Everlasting had not fixed/His cannon ‘gainst self-slaughter”) is a hinting at the possible action that the pervious metaphor points to, suicide. However, the pathos is maintained when Hamlet points to the futility of that action, his being sent to hell (i.e “’gainst self slaughter”).
Then Hamlet’s frustration gives way to depression, expressed through a familiar complaint of a fruitless existence :
How weary, stale, flat and unprofitable,
Seem to me all the uses of this world!
This idea is continued with an active condemnation of the world. Again, the pattern here is to firstly express the idea metaphorically:
Fie on't! ah fie! 'tis an unweeded garden,
That grows to seed; things rank and gross in nature
Possess it merely.
Secondly, to reinforce the idea by referencing something literal, the ease with which Hamlet’s mother has forgotten his father :
That it should come to this!
But two months dead: nay, not so much, not two:
So excellent a king; that was, to this,
Hyperion to a satyr; so loving to my mother
That he might not beteem the winds of heaven
Visit her face too roughly. Heaven and earth!
Must I remember? why, she would hang on him,
As if increase of appetite had grown
By what it fed on: and yet, within a month--
Let me not think on't--Frailty, thy name is woman!--
A little month, or ere those shoes were old
With which she follow'd my poor father's body,
Like Niobe, all tears:--why she, even she--
Hamlet then swings back to the metaphorical again, comparing his mother to “a beast that wants discourse of reason” and then falling into the literal problem:
married with my uncle,
My father's brother,
Hamlet then attacks his mother for marrying her dead husband’s brother, because he is not as great as the late King Hamlet. Taken together, his comments on his mother and his father seem to imply that Hamlet feels as if his mother never really understood the greatness of his father, either that or it was a great failing of hers to devalue his father’s memory by marrying incestuously and hastily.
That point made, the soliloquy concludes where it began, and reinforces the idea that Hamlet is heart broken, despising his situation, yet apparently unable to change it.
It is not nor it cannot come to good:
But break, my heart; for I must hold my tongue.
As Hamlet’s First, this soliloquy is helpful in setting the grounding for his procrastination and its importance could best be understood by examining how it does so.
If one accepts that Hamlet’s over active intellect was largely to blame for his madness (see this essay) the speech is especially useful.
As revealed above, the pattern to this soliloquy is that of abstract sitting beside actuality, metaphor nested between example, one in which Hamlet’s head is evidently running furiously over his situation and churning out great masses of images. He uses these to exemplify, break down and understand his situation.
But it is this abstractness of thought that leads Hamlet into his procrastination. The speech introduces the little rift between considering what is actually there and considering the images that one uses to understand what is. It is here that the detachment he displays from his situation is introduced. The more passionately he considers his situation the more crammed with images and sweeping statements they become and the further they get from reality and the harder it becomes for him to consider them.
That said, the soliloquy serves another, perhaps more practically obvious, purpose: that of explanation. It is here that the audience is made exactly aware of the situation of Hamlet. Not just in terms of his depression but also concerning the health of the state (Claudius taking the throne and marrying the Queen). In this sense the passion of frustration and the depressing, almost maddening, over use of metaphor and the characterisation of Hamlet is the context for the progression of plot. Or rather, and more ingeniously, both are occurring at the same time.