The text describes a Caesar cipher, where each letter has been shifted by a fixed number of positions in the alphabet. The key to decoding the message is to find the constant shift value used in the encryption. By analyzing the poem and looking for patterns in the letters that occur frequently, it is possible to determine the shift value and decode the message. The text presents several possible shift values and their corresponding decoded messages, which are all similar to the original poem. The conclusion is that the shift value used in the encryption is likely to be a multiple of 4.