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'.

An abiding and central concern of philosophy and religion alike is the fear that the world is alien to human beings, that nature is, in Hegel's words, 'out and out other' to 'spirit'. It's easy enough to see how 'constructivist' or 'humanist' conceptions are efforts to dispel this fear.

The garden is as good a symbol as you can find of a dialectic between spheres of experience - of culture and nature - that presuppose one another.

For me, the existentialists are important critics of 'absolutist' claims, and Heidegger and Merleau-Ponty are, at least in their later writings, also exponents of a doctrine of mystery: Being or the 'well-spring' of everything is, for Heidegger, ineffable, just as what Merleau-Ponty called 'Flesh' is for him.

I'm very sceptical about the prospects for 'big' environmental causes - 'saving the planet', halving the world's population, ending the exploitation of animals, and so on - but a person can ask him- or herself how he or she personally may exercise compassion or humility towards animals, vegetal life and so on.

It's as if, for Schopenhauer and perhaps Kant, the mind is there up and running, equipped with its categories and concepts that it then projects or smears, as it were, over what impinges upon it from the outside. This is not the image you find in, for example, Chuang Tzu: minds and nature are inseparably fused in an ever-changing whole of experience that, so to speak, constantly wells up from an indescribable source in a process that Daoists call 'the way' or 'the course'.

In all great civilizations, garden discourses have belonged to larger discourses about beauty, the good life, the relation of humankind to nature, and so on.