it is only a theoretical abstraction. There are constant market fluctuations as producers adjust to each other without being able to determine how much others will produce for sale. At most, one could say that in times of strong economic growth, when markets strongly expand, all producers can make gains from increasing output, even if the gains are unequal. But after a certain time, productive investment will "overshoot" a now saturated market demand, causing the economy to spiral into crisis again. The basis for this alternative interpretation is that as long as simple reproduction is at least accomplished, expanded reproduction permits considerable variations, possibilities, and flexibilities (elasticities); the gross profit income of enterprises can, within certain limits, be used or reinvested in many different ways without causing any critical disturbance of the economic reproduction process as a whole. The higher labor productivity is and the larger the surplus product, the more discretionary wealth exists. The less that basic necessities (food, clothing, housing, cellphones, etc.) cost as a fraction of the disposable household budget, the more funds are available to be spent optionally or saved. In addition, the extension of credit can compensate for temporary supply-demand imbalances. So while certain minimal quantitative conditions do exist for the proportionalities of outputs among different branches of production, these proportionalities can be maintained, even if the output growth rate per year drops, say from 4% to 2%. Provided that the capitalist relations of production are stable and secure, capital accumulation will continue, despite constant market fluctuations, at a slower or faster pace. Society will reproduce itself anyway, but at a lower or higher standard of living. In this case, models of economic reproduction are not a useful guide to understanding economic crises because, it is argued, Marx only intended them to show how it was possible for the whole economic reproduction process to be accomplished on the basis of the circulation of capital, by stating the minimum requirements (not the equilibrium conditions) for it. If certain quantitative assumptions are made about the growth rates of different sectors and about capital compositions, it can be proved that certain disproportions must necessarily develop. But in reality, the economic reproduction process could be interrupted or break down for all kinds of reasons (including non-economic causes, such as wars or disasters). And if disproportions occur, the economic system can also adjust to them, within certain limits. If vastly