But in our opinion truths of this kind should be drawn from notions rather than from notations. - Carl Friedrich Gauss

All the measurements in the world do not balance one theorem by which the science of eternal truths is actually advanced.

One cannot reduce to concepts the distinction between two systems of three straight lines each (directed lines, of which the one system points forward, upward to the right, the other forward, upward to the left) but one can only demonstrate by holding to actually present spatial things. Two minds cannot reach agreement about it unless their views connect up with one and the same system present in the real world

When a philosopher says something that is true then it is trivial. When he says something that is not trivial then it is false.