In 1913, LEJ Brouwer started a new approach to give a topologist's definition of the notion dimension ("Über den natürlichen Dimensionsbegriff", Journal für die reine und angewandte Mathematik, 142, 1913, pp. 146--152".) In this paper, Brouwer starts with a "Normalmenge" (Normal Set), referring to Maurice René Fréchet.

• Can anyone explain in modern terms by which properties Normal Sets are characterized?
• Where can Fréchets definition be found?