  The first two are rules of analysis and the second two rules of  synthesis. But although the analysis/synthesis structure remains,  what is involved here is decomposition/composition rather than  regression/progression. Nevertheless, Descartes insisted that it was  geometry that influenced him here: “Those long chains composed  of very simple and easy reasonings, which geometers customarily use  to arrive at their most difficult demonstrations, had given me  occasion to suppose that all the things which can fall under human  knowledge are interconnected in the same way.” (Ibid.   [Further Quotations])  