"Tinbergen's methodology was exceptional at that time and was received sometimes with scepticism. In particular J.M. Keynes (1939), at the time editor of the Economic Journal, reviewed 'Professor Tinbergen's Method' quite critically, raising as one of the fundamental points that 'The method is neither of discovery nor of criticism. It is a means of giving quantitative precision to what, in qualitative terms, we know already as the result of a complete theoretical analysis.' Of course the latter criticism illustrates precisely Tinbergen's conviction that knowledge relevant for policy making should preferably be quantitative in nature. As to 'discovery,' Tinbergen (1940) in his 'Reply' indicated that 'it sometimes happens that the course of the curves itself suggests that some factor not mentioned in most economic textbooks must be of great importance,' and he mentioned some examples. 'As to the possibility of 'criticism,' it seems to me,' Tinbergen (1940) argued, 'that the value found for one or more of the regression coefficients may imply a criticism on one or more of the theories that have been used.' In a 'Comment' to Tinbergen's 'Reply,' Keynes (1940) still held some doubts: 'that there is anyone I would trust with it at the present stage or that this brand of statistical alchemy is ripe to become a branch of science, I am not yet persuaded.' But Keynes concluded: 'No one could be more frank, more painstaking, more free from subjective bias or parti pris than professor Tinbergen... But Newton, Boyle and Locke all played with alchemy. So let him continue.' And so Tinbergen did."