As soon as we passed the entrance I saw before me not less than two hundred young persons of both sexes, habited in the peculiar garb of students, like our own. We advanced slowly and noiselessly, until we reached two vacant places, prepared evidently beforehand for us. Our entrance was not noticed by the classes, nor by those whom I afterwards recognized as teachers. All seemed intent upon the problem before them, and evinced no curiosity to observe the new comers. My own curiosity at this moment was intense, and had it not been for the prudent cautions constantly given me by Pio, by touching my robes or my feet, an exposure most probably would have occurred the first night of my initiation, and the narrative of these adventures never been written.

My presence of mind, however, soon came to my assistance, and before the evening was over, I had, by shrewdly noticing the conduct of others, shaped my own into perfect conformity with theirs, and rendered detection next to impossible.

It now becomes necessary to digress a moment from the thread of my story, and give an accurate description of the persons I beheld around me, the chamber in which we were gathered, and the peculiar mode of instruction pursued by the sages.

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.

The method of using the bow was this: The slate was shaken violently once or twice, so as to distribute the black sand equally over the white surface, and then the bow was drawn perpendicularly down the edge of the slate, very rapidly, so as to produce a quick whistling sound. The effect produced upon the grains of sand was truly wonderful to the uninitiated in the laws of acoustics. They arranged themselves into peculiar figures, sometimes in the form of a semicircle, sometimes into that of a spiral, sometimes into a perfect circle, or a cone, or a rhomboid, or an oval, dependent entirely upon two things: first, the place where the slate was held by the left hand; and second, the point where the bow was drawn across the edge. As the slate was subdivided into thirty-six compartments, by either one of which it could be held, and as there was a corresponding point, across which the bow could be drawn, there were seventy-two primitive sounds that might be produced by means of this simple contrivance. Each of these sounds inherently and necessarily produced a different figure upon the slate, and there were consequently just seventy-two initial letters in the Aztec alphabet.

The mode of instruction was extremely simple. A word was pronounced by the aged teacher at the front of the stage, written upon his slate, exhibited to the scholar at the black tablet, and by him copied upon it. The whole class then drew down their bows, so as to produce the proper sound, and the word itself, or its initial letter, was immediately formed upon the slate.

After the seventy-two primitive letters or sounds had been learned, the next step was the art of combining them, so as not only to produce single words, but very often whole sentences. Thus the first hieroglyphic carved upon the tablet, on the back wall of the altar, in Casa No. 3 (forming the frontispiece of the second volume of Stephens's Travels in Central America), expresses, within itself, the name, date of birth, place of nativity, and parentage, of Xixencotl, the first king of the twenty-third dynasty of the Aztecs.

The hieroglyphics of the Aztecs are all of them both symbolical and phonetic. Hence, in almost every one we observe, first, the primitive sound or initial letter, and its various combinations; and, secondly, some symbolic drawing, as a human face, for instance, or an eagle's bill, or a fish, denoting some peculiar characteristic of the person or thing delineated.

But to return to the Hall of Students. The men and women on the stage were placed there as critics upon the pronunciation of each articulate sound. They were selected from the wisest men and best elocutionists in the kingdom, and never failed to detect the slightest error in the pronunciation of the tutor.