After a brief search I found the full-text online. It was written during the height of popularity for mysticism and occult magic. Wilde's messages were transcribed through automatic writing and a ouija board.
The automatic writers were able to access such witticisms as:
Being dead is the most boring experience in life. That is, if one excepts being married or dining with a schoolmaster.
I'll definitely be reading through the rest of them over the weekend!