The scholars were mostly young men and women, averaging in age about twenty years. They all wore the emblem of royalty, which I at once recognized in the _panache_ of Quezale plumes that graced their heads. They stood in semi-circular rows, the platform rising as they receded from the staging in front, like seats in an amphitheatre. Upon the stage were seated five individuals--two of the male, and three of the female sex. An old man was standing up, near the edge of the stage, holding in his hands two very cunningly-constructed instruments. At the back of the stage, a very large, smooth tablet of black marble was inserted in the wall, and a royal personage stood near it, upon one side, with a common piece of chalk in his right hand, and a cotton napkin in the left. This reminded me but too truthfully of the fourth book of Euclid and Nassau Hall; and I was again reminded of the great mathematician before the assembly broke up, and of his reply to that King of Sicily, who inquired if there were no easy way of acquiring mathematics. "None, your Highness," replied the philosopher; "there is no royal road to learning." Labor, I soon found, was the only price, even amongst the Aztecs, at which knowledge could be bought. Each student was furnished with the same species of instruments which the old man before-mentioned held in his hands. The one held in the left hand resembled a white porcelain slate, only being much larger than those in common use. It was nearly twenty inches square, and was divided by mathematical lines into thirty-six compartments. It was covered over with a thin crystal, resembling glass, which is found in great quantities in the neighboring mountains, and is perfectly transparent. The crystal was raised about the one eighth of an inch from the surface of the slate, and allowed a very fine species of black sand to move at will between them. The instrument carried in the right hand resembled the bow of a common violin, more than anything else. The outer edge was constructed of a beautiful yellow wood, polished, and bent into the arc of a quarter circle; whilst a mass of small cords, made of the native hemp, united the two ends.