Quetzalcoatl was skilled in many arts, having invented gem-cutting and metal-casting. He furthermore originated letters and invented the Mexican calendar. The legend which describes the latter states that the gods, having made men, thought it advisable that their creatures should have some means of reckoning time, and of regulating the order of religious ceremonies. Therefore two of these celestial personages, one of them a goddess, called Quetzalcoatl to counsel with them, and the three contrived a system which they recorded on tables, each bearing a single sign. That sign, however, was accompanied with all necessary explanations of its meaning. It is noticeable that the goddess was assigned the privilege of writing the first sign, and that she chose a serpent as her favorite symbol. Some accounts represent that Huemac was the temporal king, or at least associated with Quetzalcoatl in the government; the latter occupying the priestly as well as the kingly office. Sahagun calls the associate ruler Vemac. At all events, Quetzalcoatl had an enemy, the deity Tezcatlipoca, whose worship was quite opposite in its character to that of Quetzalcoatl, being sanguine and celebrated with horrid human sacrifices. A struggle ensued in Tulla (Tollan) between the opposing systems which resulted favorably to the bloody deity and the faction who sought to establish his worship in preference to the peaceful and ascetic service of Quetzalcoatl. Tezcatlipoca, envious of the magnificence enjoyed by Quetzalcoatl, determined upon his destruction. His first appearance at Tulla was in the _rôle_ of a great ball-player, and Quetzalcoatl, being very fond of the game, engaged in play with him, when suddenly he transformed himself into a tiger, occasioning a panic among the spectators, in which great numbers were crowded over a precipice into a river, where they perished. Again the vicious god appeared at Tulla. This time he presented himself at the door of Quetzalcoatl’s palace in the guise of an old man, and asked permission of the servants to see their master. They attempted to drive him away, saying that their god was ill. At last, because of his importunities, they obtained leave to admit him. Tezcatlipoca entered, and seeing the sick deity, asked about his health, and announced that he had brought him a medicine which would ease his body, compose his mind, and prepare him for the journey which Fate had decreed that he must undertake.[429] Quetzalcoatl received the sorcerer kindly, inquiring anxiously as to the journey and the land of his destiny. His deceiver told him that the name of the land was Tullan Tlapalan, where his youth would be renewed, and that he must visit it without delay. The sick king was moved greatly by the words of the sorcerer, and was prevailed upon to taste the intoxicating medicine which he pressed to his lips. At once he felt his malady healed, and the desire to depart fixed itself in his mind.