The lesson was that of the appropriate self. While his exploration did bring him closer to the generating power behind the light, he would have been well advised to explore this realm attached to a more appropriate identity. Instead, he chose a self -- the body -- which was geared to resist the very nature of the reality he explored with it. This is like wearing a leisure suit into the Arctic.
Explore realities without number; but first, seek selflessness. For every level of form which is there in creation to discover, there is a level of identity with its creation. Playing in traffic as a paraplegic, rather than as a driver or as a city engineer, defeats the purpose of integration and makes for rough times on the path. Seek selflessness and the appropriate self. As you are free to have whatever self you can imagine, prefer with courage those self-patterns which will add harmony to existence.