Most central banks nowadays claim to abide by the principle of transparency, yet the world of central banking retains an element of inscrutability. This partly reflects the nature of the subject. Central banking is a weightier and more technical business than chicken farming or running a bus company. Though central banking might not be as delicate as brain surgery, or as complicated as the exploration of space, it is evidently a highly skilled trade. Until transparency became fashionable in the late twentieth century, central bankers did little to promote a wider understanding of their role. Shunning the limelight, their rare public statements were notable for brevity and calculated vagueness.