1 Geometrical Structure of M.- 2 Skew-Symmetric Linear Transformations and Electromagnetic Fields.- 3 The Theory of Spinors.- A.1 The Euclidean Topology.- A.3 The Path Topology.- Appendix B Spinorial Objects.- B.1 Introduction.- B.2 The Spinning Electron and Dirac's Demonstration.- B.3 Homotopy in the Rotation and Lorentz Groups.- References.- Symbols.