Theoretical physicists have recently described themselves as aspiring to a "theory of everything'. But more than two centuries ago Kant offered in the Dialectic of his Critique of Pure Reason a systematic diagnosis of a certain kind of transcendental illusion about absolute totalities, an illusion to which we are prone whenever we try to think about the world as a whole. I propose to look afresh at Kant's thought and ponder its implications for contemporary cosmological theorizing, and, conversely, to ask whether modern science can throw any light on his dark musings.¹