On the fifth day after the messenger had been dispatched, a courier ran into the camp, just as the caravan was about to start, and handed to the chief merchant what looked to Roger like a portfolio. This, indeed, was something of its character. It consisted of two thin boards, within which was a sheet of paper. It contained a number of paintings and signs, of which Roger could make nothing, but the merchants informed him that it expressed the satisfaction of the King of Tezcuco, at the news that had been sent him of the arrival of a strange white personage in the land; that the priests would consult the auguries, and decide whether it boded well or ill for the country; and in the meantime that they were to journey on to Tepeaca, where they would be met by an envoy, charged to receive the white stranger and to conduct him to Tezcuco. The merchants themselves were only able to gather the general contents of this picture dispatch, but the slave who had drawn the one sent forward interpreted every sign and color; for Roger found that colors, as well as signs, had their meaning. He learned from the merchants that this picture writing was a science in itself, and that it needed years of instruction and labor to acquire it. In every town and village there were certain persons skilled in the art, so that messages of all kinds could be sent to the capital, and orders and instructions received. The national archives were entirely written in this manner, and in the temples were immense stores of these documents, affording information of every event of interest, however minute, in the history of the people. The caravan now pushed on rapidly. After traveling, as Roger calculated, nearly a hundred miles from the sea, the ground began to rise rapidly, and in a single day the change in temperature was very marked. Roger felt the sense of listlessness and oppression, which had weighed upon him while crossing the low country, pass away as if by magic; and it seemed to him that he was again breathing the air of Devonshire. The vegetation had greatly changed. The vanilla, cocoa, and indigo had disappeared, and trees totally different from those of the plain met his eye. Another day's march, and they were four thousand feet above the sea. Here everything was green and bright, showing that rain constantly fell. Groves of a tree of rich foliage, which was, the merchant told him, the liquid amber tree, grew near the road; while on both sides lofty mountains rose precipitously to a great height, their summits being clothed in snow. Some of these, he heard, had in times past burnt with terrible fires, and vast quantities of melted rock flowed over the country, carrying destruction in its course. In many cases the road was a mere track winding along the side of these mountains, with precipices yawning below.