The great controversy regarding many episodes in Tanach which record hearing or seeing an angel, such as the story of Avraham and the three angels at the beginning of Parshat VaYera, is part of a broader and more fundamental issue regarding the relationship between the physical and spiritual realms of being. The Rambam and the Ramban disagree about this metaphysical issue, and their views are relevant to a host of issues, such as the nature of man as a created being, the world hereafter, the ressurection of the dead, and can angels be seen in this world? The ramban's view on an angel appearing to man as a Malbush is esoteric and mystical. The Rambam as the rationalist par excellance, cannot fathom a spiritual being in a physical form.