No doubt the photo analysis has been intriguing.... That being said, it doesn't appear that we have any sense of closure as to the true intended meaning of this symbolism as it pertains to the author's intent. While the tomb is without question a representation that is personal to the creator, it seems quite evident that the message is a Universal one that would have implications for all of humanity. Sort of like the author uncovered a profound truth about our cosmic fate and it was so near and dear to his heart that he wanted it recorded on his eventual resting place, whether he lived to see these 'events' or not.