The current expression of “flatten the curve” has similarities with mid-twentieth century macro-economic policy that can aptly be characterized as “shaping macro phenomena.” To the extent these similarities hold, the historical-epistemological analysis of this kind of macro-economic policy can provides us with a better understanding of the preconditions for the effectiveness of the current COVID-19 flatten-the-curve policy. Policy in terms of shaping a phenomenon presumes that the phenomenon in question exists and has a certain shape that can be moulded. This (...) moulding, however, is not assumed to be performed directly on the shape itself, but by operating the mechanism that generates this shape, and which is also believed to exist. Therefore the precondition for this kind of policy is knowing the mechanism at work. The knowledge of this kind of intervention needed to change the shape in a desired direction, this knowledge about the mechanism, is assumed to be captured by a mathematical model on which several policies can be tried out to see which one leads to the desired shape. Mid-twentieth century macro-economic policy aimed at shaping the business cycle, and hence was based on the belief in the existence of a business cycle mechanism. With the loss of the belief in the existence of such a mechanism, the policy of shaping the business cycle disappeared with that too. This paper unpacks this history and shows how this policy based on mechanical reasoning, which originated in natural science, was gradually replaced by an approach that takes into account non-natural aspects of human behaviour. (shrink)