Identify a story about an emperor and a gifted poet destined to write a poem for him

I remember reading a great story somewhere in around year 2006.. although I believe it originates from a much earlier time, like somewhere in 20th century. The story was likely to be a part of a bigger book, but it was pretty self-sufficient, and about 20 pages of A4 or so long.

The plot was rather strange..

What I remember is that the action takes place in some kingdom or empire, ruled by an emperor. No one have ever seen this emperor for he is too great to see him. In the name of him, a big and prospering city of his country gets totally destoryed to build a super huge garden and palace in place of it. Also, the emperor wants the best talented poet to write the most beautiful poem for him to proclaim his glory.

Then somehow the plot is telling us about a boy which studies in a school for poets, where they are teached various disciplines, including some mental and meditative ones. During one of the sense deprivation sessions he undergoes some kind of sexual intercourse with grandmother (with the vision of her), for what he is considered to have the required traits to be the poet for the great emperor.

The boy (I believe he had matured to this moment already) and some of his schoolmates are relocated into the emperors new palace, where they are alowed to live in the beautiful garden (the garden was full of houses and places to spend time). They were not allowed to look around when they were lead there originally, they had to look down on their foot for some reason. Also, upon arrival, some silver threads were slithered inside the inner sides of their thighs, preventing sexual desire. Some later in the text they are removed and he has some sex with someone, I do not remember exactly.

During living in the garden, the main character has encountered some girls, got his best frend killed (i do not remember how or by whom), and all in all, has grown to hate the emperor. Then, on one occasion, he is invited into the palace to meet the emperor in person. When he comes into the room, there are several people sitting, and they have a mask which they pass from each one to another when they speak, and the one wearing the mask at the moment is the emperor. So, turns out there is not even any emperor at all. I do not remember what they were talking about.

Then the protagonist is coming back to his living place in the garden and begins to write the poem, being full of hate. He writes a very destructive poem about the emperor, accusing him of many many bad things he done, starting from destroying the whole city and killing everyone in it just to build his great residence there (the text of the poem is present in full in the text of the story). So, he writes the poem and someone kills him.

The servants bring the paper with the poem to the emperor, he reads it and says "what a wonderful poem!" - or something like this, then they change just 1 (one!) word in the poem and it is totally flipped in its meaning. That had a magical effect on me - the reader - they change just a single word and it really reads like a very glorifying poetry, singing a beautiful hymn for the greatness and goodness of the emperor.

I believe the description I have managed to write above is rather characteristic, although I could not find the text or mentions about it anywhere in the net. I also believe that it was probably written by some writer from Geat Britain, from 19th or 20th century, although I am totally unsure of that.

Thanks in advance!