There's the idea that everything is defined in relation to something else, except the Dao, which is itself. As a corollary, anything you can name, i.e. define,

There's the idea that everything is defined in relation to something else, except the Dao, which is itself. As a corollary, anything you can name, i.e. define, isn't the Dao. In the ddj it's not said explicitly like this but it's something that can be pieced together from various chapters.