[en] The trial function psi in the Rayleigh - Ritz variational principle, delta< psi|(H-E)|psi>=0, is restricted to a continuous superposition of Slater determinants phi(t), psi = ∫ dt f(t) phi(t). The variation delta is performed upon the path [phi(t)]. It is found that time-dependent Hartree-Fock (TDHF) solutions phi(t) are reasonably optimal choices to make the Rayleigh - Ritz functional stationary. (author)