Money capital is needed to pay for factors of production, such as raw materials, plant, energy, and labour. Commodities may then be produced which are more valuable than the cost of all the inputs; surplus value has thus been added. The commodities are sold (turned back into money) so that surplus value leads to reinvestment. Accumulation occurs with each circuit of capital, and the spatial integration of different productive nodes within society gives concrete substance to the different moments of the money circuit of capital (De Angelis (1998) Conf. Paper, Eur. Ass. Evol. Pol. Econ.). As the circuit of capital expands into effective markets, the circuit is diversified (Lee (2006) TIGB 31, 4). If the circuit of capital is broken, or if there is over-accumulation, capitalists might ‘switch circuits’; see T. Hall (2001). D. Harvey (1996) discusses the different temporalities of short-term financial, medium-term industrial, and long-term infrastructural capital, and the pressures and distortions that these can create within the overall circuit of capital.