Thus, in periods after large new gold discoveries – for example, following the California Gold Rush of 1849, and again in the 1890’s, when new mining techniques opened up South African, Alaskan, and Australian reserves – the classical gold standard had a mild inflationary bias. In an era of paper money, however, the link to a physical stock of some precious metal – or, indeed, some other commodity – does not exist, and there should be no reason why a central bank cannot aim at an overall inflation rate.