What impressed me about Plato and Sartre was their conviction that we should live our lives in the light of big truths about reality and human existence.

Does the unmistakeable intent of Versailles to proclaim dominion over nature destroy its aesthetic appeal, as Schopenhauer thought? Does the greenness of the lawn lose its allure when we learn how much water, sorely needed elsewhere, it uses? And historical shifts in garden taste - from formal, 'French' gardens to 'Capability' Brown's landscapes, for instance, or from the elaborate gardens of imperial Kyoto to Zen 'dry' gardens - register important changes in philosophical or religious attitudes.

The demands of the economy, and more recently those of political correctness and the diktat against ever offending anyone, are not conducive to a classroom or university seminar climate in which genuinely free and critical reflection on how to live prospers.

While I am happy to make the occasional foray into educational philosophy - writing, for example, of the difficulty in the contemporary context for a teacher to be 'truthful' - it is more the personal conduct of a life than social institutions that I am concerned to examine.

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.

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.

In the doctrine of the world and humankind as 'will to power and nothing else', Heidegger identified not an antidote to nihilism, but the completion of it. For what can be more destructive of truth and value than the doctrine that these are simply the impositions on the world of human exercises of power?