Theories of gravity, first Newtonian one, and later General Relativity, are definitely cornerstones of modern physics. After triumphant verification of General Relativity it may seem pointless to further question our understanding of gravity. However, there are some fundamental issues that we still lack to understand. These include the origin of inertia and the value of the gravitational constant, which was pointed, among the others, by Schroedinger and Dirac. In the talk I will present two preliminary attempts to fill in the gaps in our understanding of gravity by Sciama and by Dicke (but actually originated by Mach and Einstein).