Question

according to your cartesians followers of descartes, everything is performed by an impulsion, of which we have very little notion; and according to sir isaac newton, it is by an attraction, the cause of which is as much unknown to us. at paris you imagine that the earth is shaped like a melon, or of an oblique figure; at london it has an oblate one. a cartesian declares that light exists in the air, but a newtonian asserts that it comes from the sun in six minutes and a half.... the very essence of things is totally changed.... how furiously contradictory are these opinions! what is the main idea of this passage? sir isaac newton is the greatest scientist of this era. light comes from the sun in fewer than seven minutes. the followers of descartes know more than those who follow newton. people still dont understand how the world works.

Explanation:

The passage presents different and contradictory views (by Cartesians and Newtonians) on various phenomena like the cause of actions (impulsion vs. attraction), the shape of the earth, and the nature of light. It emphasizes that the essence of things seems to be in flux due to these conflicting opinions, indicating that there is a lack of a unified, clear understanding of how the world works. The first option about Newton being the greatest is not supported as the passage is about contrasting views, not about singling out Newton as the greatest. The second option about light is just one of the many examples and not the main idea. The third option is incorrect as the passage doesn't suggest one group (Cartesians) knows more than the other (Newtonians), but rather shows their views are different and contradictory.

Answer:

People still don't understand how the world works.