Barthes' process of looking, analyzing his own reactions, changing his perspective according to the results the analysis, looking again, and repeating the process is as instructive to his readers as are his conclusions. The photograph is like the surface of a pool which reflects our ideas. Barthes sought reflections of the idea that would most affect him, which he discovered was his own Death. A Narcissus who enters the pond to become one with his beloved would drown. The equivalent to drowning while looking at a photograph would be madness.
Madness is a death of one's identity.
The Sun's principles are the virtues. Three years, there is no food. The photograph seemed to be a portal into the mythical underworld of the Dead for Barthes. This idea was reinforced in his use of Greek mythology with underworld themes. Barthes compared his experience, of going deeper inside himself to find a universal essence of photography, with Sisyphus' punishment in Hades.