THESE DAYS the streets of Berlin run red with the blood of sacred cows. On June 24th Lars Klingbeil, the finance minister, unveiled plans to borrow vast sums for a debt-funded €500bn ($580bn) infrastructure programme and a giant rearmament scheme. The world’s third-largest economy is jettisoning its hard-earned reputation as Europe’s champion of flinty austerity. It is a bold move, and one welcomed by Germany’s allies and the financial markets. But it is not without risks.