Movement...
The Torascan pyramid of Tzin Tzun Tzan has five circular platforms, one for each of their important gods. Four of these are earth, fire, water, and wind. The most important was reserved for the center position in the array of platforms. This was the god of movement.

Everywhere, Monarchs in Motion
We were overwhelmed with movement of butterflies. They filled the town of Angangueo. They mobbed the flower patches of Eupatorium and Senecio on the way to the colonies. Approaching Pelon they were especially active. Rivers of them fly along the Xoconusco Road and then swing back toward the mountain on the Macheros Road. Millions cascade from clusters at Rosario and especially Pelon. Everywhere monarch butterflies were in motion--why?

But Why?
Most of the year their movement is more limited. They do not venture so far from the colony. Most of the year dew--and sometimes rain and fog--water--is available to them in the colony or close-by llanos. This is the time of the year when the habitat is dry as a bone. When one visits open water sources below the mountains they are mobbed with thirsty butterflies. But if thirst drives this behavior, why not fly down to the water, drink, and then return? Why the large rivers of circulating butterflies that so dazzle us humans? Why is this behavior so prevalent at this time, late in the season?

It may be a simple answer: They are warming their engines. They are practicing flying. They are developing--improving--their flight muscles. It is only an unproven speculation, but they may be exercising.