From specimens of these amulets preserved in museums it is seen that any greenish stone was selected, preferably those yielding a high, vitreous polish, as jadeite, turquoise, emerald, chlormelanite or precious serpentine. The color gave the sacred character, and this, it seems to me, was distinctly meant to be symbolic of water and its effects, the green of growing plants, and hence of fertility, abundance and prosperity. =31.= There is another symbol, still venerated among the present indigenous population, which belongs to Nagualism, and is a survival from the ancient cult; this is the Tree. The species held in especial respect is the ceiba, the silk-cotton tree, the _ytzamatl_ (knife-leaved paper tree) of the Nahuas, the _yax che_ (green, or first tree) of the Mayas, the _Bombax ceiba_ of the botanists. It is of great size and rapid growth. In Southern Mexico and Central America one is to be seen near many of the native villages, and is regarded as in some way the protecting genius of the town. Sacred trees were familiar to the old Mexican cult, and, what is curious, the same name was applied to such as to the fire, _Tota_, Our Father. They are said to have represented the gods of woods and waters.[48-*] In the ancient mythology we often hear of the “tree of life,” represented to have four branches, each sacred to one of the four cardinal points and the divinities associated therewith. The conventionalized form of this tree in the Mexican figurative paintings strongly resembles a cross. Examples of it are numerous and unmistakable, as, for instance, the cruciform tree of life rising from a head with a protruding tongue, in the Vienna Codex.[48-†] =32.= Thus, the sign of the cross, either the form with equal arms known as the cross of St. Andrew, which is the oldest Christian form, or the Latin cross, with its arms of unequal length, came to be the ideogram for “life” in the Mexican hieroglyphic writing; and as such, with more or less variants, was employed to signify the _tonalli_ or _nagual_, the sign of nativity, the natal day, the personal spirit.[48-‡] The ancient document called the Mappe Quinatzin offers examples, and its meaning is explained by various early writers. The peculiar character of the Mexican ritual calendar, by which nativities were calculated, favored a plan of representing them in the shape of a cross; as we see in the singular _Codex Cruciformis_ of the Boturini-Goupil collection. =33.= But the doctrines of Nagualism had a phase even more detestable to the missionaries than any of these, an esoteric phase, which brought it into relation to the libidinous cults of Babylon and the orgies of the “Witches’ Sabbaths” of the Dark Ages. Of these occult practices we of course have no detailed descriptions, but there are hints and half-glances which leave us in no doubt.