There is a difference of feeling between saying "the circle is a scientific or philosophical idea" and saying, "the circle is an archetypal idea." Archetypal adds the further implication of basic root structure, generally human, a necessary universal with consequents. The circle is not just any scientific idea; it is basic, necessary universal. Archetypal gives this kind of value. James Hillman 
We arrive to circles with a point of view. A tension arises. Circle scribing universal form. Circle embodying a particular meaning for the people of a specific time and place.
The value Hillman alludes to arises not from interpreting. Instead, holding close to the image. This allowing is to enter the circle. We may intuit a commonality emerging from the shared heritage of our human minds. Beyond that, as he says: “An archetypal quality emerges through (a) precise portrayal of the image; (b) sticking to the image while hearing it metaphorically; (c) discovering the necessity within the image; (d) experiencing the unfathomable analogical richness of the image.” 
 James Hillman, “Inquiry into Image,” Spring, 1977, p 82. (As cited in A Blue Fire, edited by Thomas Moore, 1989. 26-27.)
Album: Petroglyph Circles
Below, "Necessity within the Circle" Hart-Warner Uplands, Lake County