not a regular movement; sometimes a long series of years passes without notable change, then come moments of rapid transformation. On this difference Saint-Simon has founded a distinction between organic periods (of slow change) and critical periods (of rapid change).
CHAPTER III
CONSTRUCTIVE REASONING
I. The historical facts supplied by documents are never enough to fill all the blanks in such schemes of classification and arrangement as we have been considering. There are many questions to which no direct answer is given by the documents; many features are lacking without which the complete picture of the various states of society, of evolutions and events, cannot be given. We are irresistibly impelled to endeavour to fill up these gaps.
In the sciences of direct observation, when a fact is missing from a series, it is sought for by a new observation. In history, where we