I've tried several times reading The Dialectics of Enlightenment, it is simply to dense for me and my grounding in philosophy is really not that strong. I've looked at the summary in SEP, and need help understanding this:
“Myth is already enlightenment, and enlightenment reverts to mythology.” The first thesis allows them to suggest that, despite being declared mythical and outmoded by the forces of secularization, older rituals, religions, and philosophies may have contributed to the process of enlightenment and may still have something worthwhile to contribute. The second thesis allows them to expose ideological and destructive tendencies within modern forces of secularization, but without denying either that these forces are progressive and enlightening or that the older conceptions they displace were themselves ideological and destructive.
I think this means that (some) myths where used to make sense of the world with the intellectual toolkit available, and that the belief in enlightenment as a thing on its own (versus an ongoing process where people try and fail more or less) is the myth, but I'm not sure.
Earlier in the summary it says:
According to Horkheimer and Adorno, the source of today's disaster is a pattern of blind domination, domination in a triple sense: the domination of nature by human beings, the domination of nature within human beings, and, in both of these forms of domination, the domination of some human beings by others. What motivates such triple domination is an irrational fear of the unknown: “Humans believe themselves free of fear when there is no longer anything unknown. This has determined the path of demythologization … . Enlightenment is mythical fear radicalized”
So one could say that myths where, or are, an attempt to handle fear of the unkown and enlightenment as practiced is often another way of doing the same. So enlightenment would be guided by the same forces that shaped religios thought and other myths, defining the quesions that are asked and the ones that are not. But does it follow from here that enlightenment is myth? I don't really see it, only sorta-kinda.
This just to give you an idea of where I stand and where my reading took me. Ultimately, I want to understand what Adorno and Horkheimer meant with “Myth is already enlightenment, and enlightenment reverts to mythology.”