That's exactly what it is, and I'm afraid there is no message other than what it actually says, nothing .....but people have got vivid imaginations and one of the great skills of the human mind is its ability to fill in gaps ....which explains why people take nonsense and try to make sense of it ... and this is exactly where their subconscious may play its part ...
^^ I agree completely.
It is only natural for the human mind to try and fill in the gaps, it cannot comprehend something that has no sense or purpose, hence the purpetual search for the meaning of life, and the reason as to why we are on the planet. However, thats for another discussion...
it appears the guy just took some shrooms, and let his mind take him, delving deep into his subconsious. A persons artwork will often display his/hers view on life through his subconsious, and also tells you what sort of person they are too, as well as telling you about yourself.