Over a 100 years ago in his paper Space and Time Hermann Minkowski revealed the profound physical meaning of the relativity postulate—the experimental fact that physical phenomena are the same in all inertial reference frames implies that every inertial frame has its own space and time, which in turn implies that the Universe is an absolute four-dimensional world in which all moments of time have equal existence due to their belonging to the fourth (time) dimension. Since then there has been no consensus on the reality of this absolute world, which we now call Minkowski spacetime or simply spacetime. One might be tempted to interpret this situation in a sense that the question of the dimensionality of the world is so deep that we seem unable to comprehend it fully, which might be a manifestation of the first hints that there might exist some limits of our understanding of the world. I will argue that human abilities to understand the physical world are much greater than what most think by examining the issue of the reality of spacetime and showing that none of the experiments which confirmed the kinematic relativistic effects would be possible if the world were not four-dimensional. Therefore, facing the ultimate judge—the experimental evidence—allows us (i) to realize fully that in 1908 Minkowski had a better (than the present) understanding of the profound physical meaning of Einstein's special relativity as a theory of an absolute four-dimensional world, and (ii) to settle the issue of the reality of spacetime once and for all.