- Our tendency to artificially beautify reality in order to conceal the truth.
- Our tendency to be false to others because of our failure in being true to ourselves.
- Our lack of honesty in facing up to the truth, the most fundamental one being that we are going to die; and
- Death itself - mortality and how we humans (fail to) deal with it.
Shakespeare makes that last two points overtly right at the beginning:
But you must think your father lost a father,
That father dead, lost his, and so shall be
Until the general ending.
Therefore cease laments, it is a fault
‘Gainst heaven, fault ‘gainst the dead, a fault ‘gainst nature,
And in reasons common course most certain,
None lives on earth, but he is born to die.
But nowhere in the play does he interlace the themes so completely as in Gertred's description of Ofelia's drowning. It's actually pretty funny: I doubt there has been anyone who has taken a closer look at that monologue and didn't think, "Oh for chrissakes people, don't just stand there and watch her... somebody jump in and save her!!" And I used to write this off as "Shakespearean" or poetic license or with some such dismissiveness. Wrong.
Here's a thought: How 'bout entertaining the notion that Shakespeare knew exactly what he was doing and meant it as morbidly stinging commentary. Here is the Quarto version, which is even less florid than the Folio. Read it with the four bullet points above in mind:
O my lord, the young Ofelia,
Having made a garland of sundry sorts of flowers,
Sitting upon a willow by a brook,
The envious spring broke. Into the brook she fell,
And for awhile her clothes, spread wide abroad,
Bore the young lady up, and there she sat
Smiling, even mermaid-like 'twixt heaven and earth,
Chanting old sundry tunes, uncapable as it were
Of her distress. But long it could not be
Till that her clothes, being heavy with their drink.
Dragged the sweet wretch to death.