Why is a raven like a writing desk?

Edgar Allen Poe is like a writing desk
Edgar Allen Poe wrote on a Raven
If something sometimes comes after you,
Then sometimes monsters won't offer you hospitality
Because little blue oranges
And sky
Like a winding little birdie
Conk shells
And red lights
And blaring silver sentences
GALLOPING
GALLOPING
GALLOPING
GALLOPING
Lollipop
why is a raven like a writing desk?