Abstract: The theory of observational relativity (OR), based on the logical prerequisites different from that of Einstein's theory of special relativity, has derived the general Lorentz transformation (GLT) that is exactly the same as the Lorentz transformation in form. The GLT has generalized and unified the Lorentz transformation and the Galilean transformation, shed light on the corresponding relationship between different observation systems and between different theoretical systems in physics, and endowed Bohr's correspondence principle with more universal significance. On the basis of the theory of OR and Bohr's correspondence principle, this paper develops the principle of general correspondence (PGC). Under the principle of PGC, the theory of OR is extended from inertial spacetime to gravitational spacetime, Einstein's theory of general relativity is extended from the optical observation system to the general observation system, and finally, the theory of general observational relativity (GOR) has been established that is isomorphically consistent with Einstein's theory of general relativity. The theory of GOR provides us with a new insight into Einstein's general relativity: the objective and real spacetime is never curved; like all relativistic phenomena in observation, the so-called spacetime curvature is not objectively physical reality, but an observational effect resulting from observational locality. The theory of GOR has generalized and unified the two great theoretical systems, Newton's theory of universal gravitation and Einstein's theory of general relativity. In the theoretical system of GOR, Newton's theory of universal gravitation and Einstein's theory of general relativity are both partial theories that Hawking termed in his book "A Brief History of Time", and belong to different observation systems: the Newton's theory is the product of the idealized observation system; while Einstein's theory is the product of the optical observation system. According to the theory of GOR, different observation systems have different degrees of observational locality, so that their observed gravitational spacetimes present different degrees of curvature. The speed of light is limited (c < ∞) and therefore the optical observation system has observational locality, which is why Einstein's gravitational spacetime looks somewhat curved; the idealized observation system has no observational locality and therefore Newton's gravitational spacetime represents the objective and real gravitational spacetime. In the sense of the PGC, the theory of GOR has strict corresponding relationships with both Newton's theory of universal gravitation and Einstein's theory of general relativity: in the case of optical observation, the field equation of GOR is strictly reduced to Einstein's field equation, and the geodesic equation of GOR is strictly reduced to Einstein's geodesic equation; in the case of idealized observation, the field equation of GOR is strictly reduced to Newton's field equation (i.e., Newton's law of universal gravitation in the form of Poisson's equation), and the geodesic equation of GOR is strictly reduced to Newton's geodesic equation in the form of Newton's second law. Such strict corresponding relationships show that the theory of GOR is logically consistent with both Einstein's theory of general relativity and Newton's theory of universal gravitation. Meanwhile, such strict corresponding relationships corroborate the logical self-consistency and theoretical validity of GOR. The theory of GOR signifies that human beings and the physics they create have to reexamine Newton's theory of universal gravitation and Einstein's theory of general relativity, to reexamine Einstein's scientific predictions based on his general relativity, and to reshape human view of nature.