Re-inventing universal gravity law from a second Kepler's principle of planetary motion

Kepler's second law -covering constant ellipse sector area within a unit time -is pretty much well known fact. However as it is stated, it is likely a geometrical principle, rather than a physical one. Also it is hard to understand root causes why covered area per unit time is constant. In this paper I try to map Kepler's second principle into a more physical one, which explains better the root causes of phenomena and gives more insight into gravity law.