I have spent a good deal of time criticizing the idea of a “perennial philosophy”, the idea (expressed by Ken Wilber and others before him) that the great sages of the world have always basically agreed on the really important things. In the past I had said there were perennial questions but with different answers; now I’m not even sure whether that is the case.

And yet I am struck by a particular phenomenon from which the perennialists draw a great deal of inspiration – and that is the pervasive influence of nondualism. “Nondual” is a literal English translation of the Sanskrit a-dvaita, the name of Śaṅkara’s school of Vedānta philosophy. But the core idea of nondualism has been asserted by a very wide range of philosophers around the world – from people who could never have heard of Śaṅkara, to Śaṅkara’s enemies.