Thaw and resolve itself into a dew!
Or that the Everlasting had not fix'd
His canon 'gainst self-slaughter! O God! God!
How weary, stale, flat and unprofitable,
Seem to me all the uses of this world!
From the play's beginnings, Hamlet is distressed. Here, his desire for his "flesh" to "melt" and dissolve into "dew" registers his anguish over his father's death and his mother's remarriage to his uncle. Clearly, Hamlet's thoughts here are suicidal and register some mental and emotionally instability. We also know from his earlier conversation with Gertrude and Claudius that he's been in a melancholy mood.
History Snack: Elizabethans believed the human body was made up of four basic elements, called humors: phlegm, blood, yellow bile, and black bile. These elements were supposed to influence a person's disposition and mood. Hamlet seems to be suffering from what Elizabethans referred to as "melancholy," which was associated with too much "black bile" in the body. This state led to lethargy, irritability, distorted imagination, and so on. Basically, it sounds a lot like what we call "clinical depression" today.
Textual Note: Some modern editions of the play read "sullied flesh" instead of "solid flesh." This is because the first folio (published 1623) edition of the play (which reads "solid") is slightly different than the first quarto (published 1603) edition, which reads "sallied." Modern editors who prefer the first quarto reading update the word "sallied" to "sullied." Both words seem to work so why are we making a big deal out of this? Well, the terms have slightly different connotations. Some editors and literary critics prefer "sullied" flesh because it suggests that Hamlet feels that he personally has been soiled, stained, or contaminated by his mother's incestuous relationship with his murderous uncle. This has some important implications for the play's theme of "Sex."