Th'expense of spirit

 William Shakespeare

Th' expense of spirit in a waste of shame
Is lust in action; and, till action, lust
Is perjured, murderous, bloody full of blame,
Savage, extreme, rude, cruel, not to trust,
Enjoyed no sooner but despisèd straight,
Past reason hunted, and no sooner had
Past reason hated as a swallowed bait
On purpose laid to make the taker mad.
Mad in pursuit, and in possession so;
Had, having, and in quest to have, extreme;
A bliss in proof, and proved, a very woe,
Before a joy proposed; behind, a dream.
All this the world well knows, yet none knows well
To shun the heaven that leads men to this hell.  

"Th'expense of spirit" is a sonnet written by Shakespeare: it is composed of 14 lines, and so it follows the Elizabethan model.

It is organised into three quatrains (rhymed ABAB  CDCD  EFEF) and a final couplet, following the rhyme-scheme GG. The title refers to the first line of the sonnet.

In the first quatrain the poet defines lust, the main theme of the sonnet. It is described like an extreme, strong and shameful waste because, in Shakespeare's personal idea it is full of blame, savage, rude, cruel and false.  

He also says  that, on one hand, people look for lust, because they try to satisfy their desire, but on the other hand, after making lust, they recognise that it is like  a ‘dream'; an illusion that will come very quickly to an end. For this reason the poet gives to the reader an answer to his invisible question: he hates it.

The second quatrain is an explanation of this act: people lose their minds because of desire: before, they want it extremely, but finally, when they had it, they hate lust.

In the third quatrain the poet writes his idea on desire and hate, and he says that the second one takes place when desire has been finished.

Finally, he concludes negativly, writing that people know everything about lust but they aren't able to recognise it.