The Daodejing opens by undercutting itself: the Dao that can be spoken is not the constant Dao. This is not evasion but a methodological warning. If the Dao is the pattern by which things unfold, any fixed formulation will be a snapshot of something moving, and mistaking the snapshot for the thing is the characteristic error the text is written to prevent.
Wu wei is the tradition's most exportable and most mistranslated idea. Rendered literally it is non-action, which suggests doing nothing. What it actually describes is action without forcing — the difference between hacking at a joint and finding where the blade already fits. Zhuangzi's famous cook carves an ox effortlessly not because he tries less but because years of attention let him work along the natural separations rather than against them. The concept is closer to skilled flow than to passivity, and its practical claim is that most exhaustion comes from working against the grain of a situation we have not properly understood.
Ziran — often translated as spontaneity or self-so-ness — names things being as they naturally are, without contrivance. From this comes Daoism's political scepticism: the more rules, prohibitions and clever administration a state produces, the more disorder it generates, because each intervention creates new problems requiring further intervention. The Daoist ideal ruler governs so lightly that people believe they arranged things themselves.
Zhuangzi presses further than the Daodejing, and is the more playful and more radical text. He questions whether our categories track reality at all: dreaming he was a butterfly, he wakes unsure whether he is a man who dreamt of a butterfly or a butterfly now dreaming he is a man. He argues that judgements of useful and useless, beautiful and ugly, depend on perspective — the gnarled tree is useless to a carpenter, which is exactly why it lived long enough to grow vast. This is a genuine epistemological challenge, not merely a poetic flourish, and it puts him in interesting company with philosophical sceptics elsewhere.
The natural objection, pressed by Confucians at the time, is that all this risks quietism: if forcing is the problem, when should anyone act to correct an injustice? Daoists reply that wu wei is not inaction but action that does not impose, and that most attempts to force improvement produce the harms they meant to prevent. Whether that is wisdom or an excuse for withdrawal is a fair question, and it is the central line of criticism the tradition has faced for two and a half thousand years.