Charles Baudelaire, a great source of inspiration for me, wrote this (this is an English translation I found).
One of the most beautiful poems of all time, in my opinion. It represents anguish, inner torment, loss of hope. Everything is described with a heavy use of symbolism and dark imagery, something typical of the Symbolist movement (French variant of the English Decadent movement and the Italian Decadentismo), something so typical of Charles Baudelaire and his "Les fleurs du mal" (The Flowers of Evil). Spleen was a state of mind, something like depression.

Spleen

"When the low, heavy sky weighs like a lid
On the groaning spirit, victim of long ennui,
And from the all-encircling horizon
Spreads over us a day gloomier than the night;
When the earth is changed into a humid dungeon,
In which Hope like a bat
Goes beating the walls with her timid wings
And knocking her head against the rotten ceiling;
When the rain stretching out its endless train
Imitates the bars of a vast prison
And a silent horde of loathsome spiders
Comes to spin their webs in the depths of our brains,
All at once the bells leap with rage
And hurl a frightful roar at heaven,
Even as wandering spirits with no country
Burst into a stubborn, whimpering cry.
— And without drums or music, long hearses
Pass by slowly in my soul; Hope, vanquished,
Weeps, and atrocious, despotic Anguish
On my bowed skull plants her black flag."