The merest indication of the association of a circumpolar constellation with the idea of death (disappearance) and resurrection (re-appearance) is of special interest, since the ancient Mexicans located the Underworld, the “place of the dead,” in the North. Reflection showed, however, that such an association could only have suggested itself to the minds of star-observers living in southern latitudes, approximate to the equator, or in localities where the northern horizon was more or less shut off from view by intervening mountains. In such places Polaris would appear comparatively close to the boundary-line of the northern sky so that the Ursa constellations and Cassiopeia would be invisible to the local astronomers at midnight during that period of the year when one or the other of the star-groups seemingly stretched between Polaris and the northern horizon. A glance at plate I shows that, at the present time, it is about the period of the autumnal equinox that Ursa Minor would be invisible at midnight, in such localities, while Ursa Major would gradually disappear from view towards midnight, during a certain number of nights, according to latitude and locality, between the autumnal equinox and the winter solstice whilst Cassiopeia would seem to hover above the horizon. The total or partial alternate periodical disappearance of the two most familiar star-groups in the extreme North and their re-appearance after sometimes regular intervals of time could but have made a profound impression upon primitive astronomers and thinkers. Whilst the mere periodical reversal of the positions of Cassiopeia and Ursa Major suggested alternate victory and defeat, the actual though brief and partial disappearance of either star-group must have appeared to be a descent into an under-ground space, associated with darkness and death, followed by a resurrection. In his Cronica, Tezozomoc records, besides Mictlan (the land of the dead), another name for the underworld, Opochcal-ocan, literally, the place of the house to the left. This appellation can only be understood when it is realized that, in a sufficiently southern latitude, an observer, watching the setting of a circumpolar constellation below the horizon, would always see it disappear to his left and subsequently rise to his right. It is evident that in time this fact would give rise to the association of the left with the underworld, the lower region, and the right with the region above. The native idea of a dwelling in the underworld is further demonstrated by the bestowal of the symbol _calli_=house, upon the western horizon below which all heavenly bodies were seen to disappear. A definite connection between the West and one half of the North being thus established, it would naturally result that a corresponding union of the South and East would be thought of in time, and that these quarters would become associated with the rising of celestial bodies, _i. e._, with light, the Above, while the