The traditional physics and the special Theory of Relativity agree in making the geochronometry of physical Space-Time Euclidean. Many really eminent writers on the Theory of Relativity have expressed themselves in a most unfortunate way, which suggests to innocent readers that they think of Space-Time as a particular existent, with properties of its own, which acts on matter like a cue acts on a billiard-ball. Since the geo-chronometry which is to be ascribed to physical Space-Time depends entirely on the correlations between our sensa, we must not be surprised if opinions about it alter with the growth of scientific knowledge. The universal force of gravitation thus appears as a hypothesis to account for this universal divergence. It must be admitted that this hardly inspires confidence. The cash value of the distinction between physical Space-Time and its contents is that the sum total of physical events has a certain spatio-temporal structure which is the same always and everywhere.