It is indeed impossible to describe reality 'in itself', but that does not mean that our lives are answerable to nothing but our own conventions and commitments. They are answerable to a way of things that transcends the reach of our conceptual schemes.

There is no reason at all to think that creatures with very different purposes and concerns would arrive at the scientific image, and no reason at all to accuse such creatures of getting the world wrong - a point that both Chuang Tzu and Nietzsche make when comparing human and animal perspectives.

I rather shared Nietzsche's conception of the kind of individual that an ideal education should be cultivating. 'Authenticity' is not Nietzsche's term, but as used by some existentialists, it nicely captures what Nietzsche admired - the resolve of an individual person to forge his or her own 'table of values', to be emancipated from strait-jacketing conventions, traditions, and ideologies. As embodied in the 'Overman', authenticity is the antidote to 'bad' nihilism.

Certainly each side - the 'absolutists' and the 'constructivists' or 'humanists', as I've labelled them - accuses the other of hubris, and lays claim to humility. I see hubris on both sides: a pretence that we could ascend to an objective account of the world, on the one hand, and a pretence that we have the resources to live and act without a sense of there being something to which we answerable, on the other. So both sides are 'villains'.

Chuang Tzu and Heidegger both emphasise the virtue of 'spontaneity' - a sort of mindful responsiveness to things as they are. It's this notion, I suspect, that is the best bet for helping to make some sense of talk about harmony or unity with nature.

There are really three players: 'absolutists', for whom it is possible to describe reality as it anyway is; 'constructivists' or 'humanists', for whom there is nothing beyond a world that is relative to human interests and conceptual schemes; and 'ineffabilists', like myself, for whom any describable world indeed exists 'only in relation to man', as Heidegger put it, but for whom, as well, there is an ineffable realm 'beyond the human'.

I think it's true that for existentialist thinkers, appreciation of what we are - free, makers of meaning, 'issues' for ourselves, and so on - is at the same time a recognition of how we should try to live.