Einstein's Concept of relativity is formulated in 4D House, Though not in a very Euclidean 4D space. Einstein's principle of spacetime contains a Minkowski structure dependant on a non-Euclidean geometry with three spatial Proportions and 1 temporal dimension, as an alternative to the 4 symmetric spatial Proportions of Schläfli's Euclidean https://ctmitalia.net/