Ernest Dowson was one of the more famouse (or would that be infamous?) writers of the Decadent Movement, along with other fellow absinthe drinkers like Oscar Wilde, Arthur Rimbaud, and Paul Verlaine, all of whom would live fast, die young and leave a good corpse. He didn't actually produce much poetry in his short life, but this particular prose poem is a nice hymn to absinthe:

Absinthea Taetra

Green changed to white, emerald to opal; nothing was changed.

The man let the water trickle gently into his glass, and as the
  green clouded, a mist fell from his mind.

Then he drank opaline.

Memories and terrors beset him. The past tore after him like a
  panther and through the blackness of the present he saw the
  luminous tiger eyes of the things to be.

But he drank opaline.

And that obscure night of the soul, and the valley of humiliation,
  through which he stumbled, were forgotten. He saw blue vistas
  of undiscovered countries, high prospects and a quiet, caressing
  sea. The past shed its perfume over him, to-day held his hand
  as if it were a little child, and tomorrow shone like a white
  star: nothing was changed.

He drank opaline.

The man had known the obscure night of the soul, and lay even
  now in the valley of humiliation; and the tiger menace of the
  things to be was red in the skies. But for a little while he
  had forgotten.

Green changed to white, emerald to opal; nothing was changed.