Engels to Conrad Schmidt27 October 1890

Where there is division of labour on a social scale, the various sections become mutually independent. Production is, in the final analysis, the decisive factor. But as soon as trade in products becomes independent of actual production, the former follows a trend of its own which is, by and large, undoubtedly dictated by production but, in specific cases and within the framework of that general dependence, does in turn obey laws of its own, laws inherent in the nature of this new factor; it is a trend having its own phases and reacting in turn on the trend of production.

It is the same with the money market. Once trade in money becomes divorced from trade in commodities, it will — under certain circumstances determined by production and by the trade in commodities and within those limits — develop in its own way subject to the special laws and distinctive phases determined by its own nature. If, in addition and in the course of this further development, the trade in money expands to comprise trade in securities, the said securities being not simply government paper, but also the shares of industrial and commercial concerns, i. e. if the trade in money gains direct control of a section of the production by which it is largely dominated, then the reaction of the trade in money on production will be even stronger and more complex.

Now as regards the more rarefied ideological fields such as religion, philosophy, etc.; these have a prehistorical fund of what today would be termed rubbish which was taken over lock, stock and barrel by the historical period. […] And even if economic necessity may have provided the main incentive for progress in natural science and done so to an increasing extent, it would be pedantic to seek economic causes for all this primitive rubbish. The history of science is the history of the gradual elimination ofthat rubbish and/or its replacement by new, if progressively less ridiculous, rubbish.