Faraday ipse dicebat viris lineas quando, exempli gratia, de campo magnetico cogitabat. In suo opere "De lineae virium natura" (Anglice: "On the physical character of the lines of force") nos informavit anno 1852: "I cannot conceive curved lines of force without the conditions of a physical existence in that intermediate space" [emphasis addita]. Scilicet: "Non possum imaginari lineas virium curvas sine existentia physicali adiuncta in illo spatio intermediario."
