I wish to cite another accordance of the General Theory; which states that a thrown baseball or a fired bullet does not actually describe a curved or parabolic path to the earth, when projected horizontally above its surface. Instead, they actually move in straight lines which only appear to be curves and parabolas. The reason for this says Einstein, is that, 'What is 4-Dimensionally straight gives the illusion of being curved or parabolic when projected on the 3 recognized Dimensions Of Space'. These quasi 3-D parabolas and curves which are not really parabolas and curves, but instead are 4-D straight lines, are called 'geodesics'. Einstein's geodesic account of gravity is that, 'Matter causes the 4-D Space-Time continuum to curve in the area surrounding it'. This fact is formally referred to as, 'Einstein's postulate of the 4-D Space-Time metric'.
If we find this Einsteinian description of gravitation vague, it is simply because it is indeed a vague description, yielding small conceptual compromise when compared with the familiar if mysterious 'tug' of Classical Newtonian gravity. One may question, What does Relativity mean when it accounts for gravity by referencing the 4-D Space-Time metric and the curving of the 4-D Space-Time Continuum? And how does this 4-D Space-Time Continuum cause bodies to descend, or geodesically appear to descend? The 'answer' is that physicists do not understand the non-mathematical identity of Einstein's 4th Dimension; since space-time is one of the many effects of the 4th Dimension, it is not understood or recognized what the geodesic gravitational curvature of space-time is either. “The General Theory (of Relativity) presented a completely altered view of gravitation. It is viewed as a property of space rather than as a force between bodies. As a result of the presence of matter, space becomes a curve and bodies follow the line of least resistance. These 4-D lines are called ‘geodesics’.” - Isaac Asimov, THE INTELLIGENT PERSON’S GUIDE TO SCIENCE Here's what false authority says of Einstein's 4-D geodesic: "We cannot visualize such a curved space. Because humanity is not four dimensional." - The LIFE Science Library's UNIVERSE, p. 179 “The General Theory (of Relativity) presented a completely altered view of gravitation. It is viewed as a property of space rather than as a force between bodies... "As a result of the presence of matter, space becomes a curve and bodies follow the line of least resistance." These 4-D lines are called ‘geodesics’.” - Isaac Asimov, The Intelligent Person's Guide to Science Einstein's 'geodesics curvature of space-time' will not be comprehended or visualized, until Matter is recognized to be in a constant state of 4-dimensionally acclerating expansion. As simply illustrated here and abundantly verified throughout this historical - previously unrecognized - review. 
(The illustrated 4-D Mass-Field Geodesic< A return to Straight Line Euclidean geometry>. The false enigma is resolved in the recognition that the entire physical frame of reference is - 4-Dimensionally - ever enlarging, pinning the fans to their bleachers, all the cars to the asphalt in the parking lot, the city accomodating the ball park and the omnidirectionally expanding planet the city rests upon: rising up to create the illusion that the apparently curving baseball trajectory, which is actually a moving in a straight line ('geodesic'), appears to be moving in a parabolic arc. When a test object is projected straight up in the air, it does not 'slow down, turn around and return to the catcher. No indeed. The catcher - or the ground - rises up to overtake and impact the test object.
(Illustration and text excerpted from The New Gravity/ Is The 4th Dimension, copyright by K. B. Robertson, 1970 thru 2007 <in nine hard copy editions>. All rights reserved. With acknowledgement, may be produced for educational non commercial purposes.)