[Slight spoilers] Just finished Sherlock Season 4, Episode 3, The Final Problem. The characterization of Eurus Holmes is haunting. (See Baker Street Wiki: The Musgrave Ritual)
But it seems to me Eurus’s Song is not entirely satisfying. As pointed out, the tune is based on Go Tell Aunt Rhody, which I find catchy. But the lyrics is not shown in its entirety in the show, and it is not properly rhymed and does not fit the meter. Moreover, the cypher is purportedly based on the dates on the gravestone of the Holmes graveyard, and, though it is not fully spelled out, the deciphering can seem arbitrary.
Thus, I decided to write my own fan-fiction poem and propose a simple cypher. I wrote that within about 3 hours. Some of the images are inspired by the lyrics proper, and those of Go Tell Aunt Rhody.
O by the stream, look, mother goose
At last does at one gosling weep.
In shadows will want she a noose;
Of course, my friend, care not her sleep.Do kids forlorn, save someone sober,
Her favorite tree tend, which grows wild?
Her feathers fall ere this October;
Her laughter will doom that sane child.O breeze, pray not mind youngsters cunning;
Your breathing rids, kin to the mills,
The blood beside lone rivers running,
One mile around there where it kills.Do East Winds gay come to the flowers,
And siblings too play as they bath?
And does the goose find that for hours
Her babies make room for their death?
I do intend my poem to be as creepy as possible, and I hope that I did it. Actually, the Go Tell Aunt Rhody already reads creepy enough, and so are many Mother Goose tales, no wonder Agatha Christie was inspired of And Then There Were None.
If read by every four words, my poem yields:
O look at one in want of care,
Do save and tend her, ere her doom.
O mind your kin, the lone one there,
Do come and play and find her room.
This fits the rest of the story, where the plain text reveals to Sherlock that Eurus has been lonely, and indicates him to come to her room (of young Eurus’s).
My poem can fit the tune of Go Tell Aunt Rhody, though one has to read 2nd and 3rd syllables in one beat, and it probably works better when just being read out according to iambic tetrameter.
Sketchbook 