Note 6 — § 3 CONCERNING THE FULFILMENT OF THE TWO POSTULATES

Strictly speaking, I should at this juncture state in anticipation that the above investigations can manifestly also be so generalized as to be valid for the four-dimensional space-time manifold, in which all events actually take place, and that the transformation-formulæ apply to the four variables of this manifold. In these general remarks the neglect of the fourth dimension is of no importance. This statement will be justified later in § 3(b).