What kinds of items were found at a public square in temixtitlan?   "this city [temixtitlan, mexico] has many public squares, in which are situated the markets and other places for buying and selling. there is one square twice as large as that of the city of salamanca, surrounded by porticoes, where are daily assembled more than sixty thousand souls, engaged in buying and selling; and where are found all kinds of merchandise that the world affords, embracing the necessaries of life, as for instance articles of food, as well as jewels of gold and silver, lead, brass, copper, tin, precious stones, bones, shells, snails, and feathers."  —hernán cortés: from second letter to charles v, 1520a:   precious metals and animal skinsb:   fountains and statuesc:   both necessities and jewelsd:   only necessities, such as food