Sentence:  The priests who were, as I have said, the early students and inquirers, had worked out this astronomical side, and in that way were able to fix dates and to frame for the benefit of the populace myths and legends, which were in a certain sense explanations of the order of Nature, and a kind of "<WSD>popular science</WSD>." 
Meaning of the word marked with <WSD> tags:  An (interpretation) of science intended for a general audience, rather than for other scientists or students.