D O C U M E N T 2 1 9 J U N E 1 9 2 2 3 3 3 Weyl 1922a for historical discussion of Weyl’s analysis of the problem of space, see Scholz 2001, sec. 2.8. Mie suggested to generalize Maxwellian electrodynamics by allowing all Lorentz covariant (but not necessarily gauge invariant) terms, which may depend on the electromagnetic potential or on the fields, in the Lagrangian of the action integral. He hoped that the resulting nonlinear generalizations of Maxwell’s equation would allow for solutions that could be interpreted as particle-like field con- figurations (see Mie 1912a, 1912b, 1913, Born 1914). Mie’s approach had been taken up and utilized in the context of a generally covariant framework by David Hilbert (Hilbert 1915). Weyl had also fol- lowed up on the idea and investigated field equations on a generalized action principle in Weyl 1919b, §35, and Weyl 1919c. For further discussion, see Pauli 1921, §§64 and 65. Eddington suggested dis- tinguishing strictly between metric field and affine linear connection and basing the physical theory strictly on the latter (see Eddington 1921a). For details, see Doc. 12.