Inertia is defined axiomatically. The gravitational field is caused by the flow of intergalactic masses. Origin of space and time are connected with fields. The cosmos is bounded by inertia and gravitation, which is the sequence of existence of two fields, the inertial field and the gravic field as a vortex field.Gravic and inertial field combine to a unit, the gravo-inertial field. The separation in gravic and inertial components depend on the coordinate system of motion.