To begin with, these incentives to private actors may turn out to have larger and more prolonged fiscal costs than anticipated, which would adversely affect public finances in any case. But more importantly, in reality, fiscal space and borrowing limits are not fixed, as revenues can be increased through various means and credit from the Central Bank can also play a role. This is important because public investment has the power to crowd in private investment, raising productivity, incomes and taxes. The successful historical experiences described in section B followed just such a trajectory.