be too late. Similarly, the man who feels lust cannot help himself. He acts quickly and unthinkingly, but then it is too late. Unlike the fish, though, which loses its life, the man loses something even more valuable: his sanity. For, as the speaker relates, lust makes a man "mad."
In the third quatrain the speaker develops the theme of madness as it relates to lust. Whether the man is seeking to satisfy his lust, is engaging in an act of lust, or has completed an act of lust, that man will be "mad" in an "extreme" way. Although the moment of sexual activity may bring pleasure ("a bliss in proof"), afterwards the man will feel bad or sad ("a very woe"). In other words, the sexual act itself does not satisfy the man. That action will only seem like "a dream" to him. It will not seem real. And, so, he will not be satisfied.
In the closing lines of the poem, in the couplet, the speaker makes an astute observation about life. Although every man knows that lust is dangerous and that lust leads to madness, no man knows how to avoid (or "to shun") feeling lust. Anybody can become a victim to that emotion called lust. And even though one may enjoy the brief moment of sexual activity ("the heaven"), that person knows the pain and the suffering (the "hell") that will be the result of such activity. People know it is wrong. They know it is dangerous. But they do it anyway.
With this poem the speaker appears to be establishing a distinct difference between his feeling