Well, they're starting their annual journey to the Valley of Souls.

Black-and-orange, black-and-orange, black-and-orange.

Even as a kid, they struck me as foreshadowing, as little flecks of Samhain fluttering, by some act of temporal disturbance, into summer.

Danaus plexippus: known variously as the milkweed, tiger, or (for unclear reasons) the monarch butterfly.

When did butterflies first come to symbolize souls? Who can say? (They're not uncommon in Minoan glyptic art.) The reasons for the connection are certainly clear enough. Probably you could rattle off three or four, if you wanted to.

And—among other reasons—like souls, butterflies are migratory.

Well, it's September now, a fortnight to the equinox, and one by one the little lords of Samhain are beginning their 2100-mile journey to the Summerlands of the South, to their wintering-grounds in the forests of Michoacán.

There they will arrive during the early-November Days of the Dead: the souls, with their unerring homing instinct, returning right on cue. Of course local lore sees them as the souls of the dead. Of course local lore knows the valley where they overwinter as the Valley of the Souls.

What is more fragile than a soul? What, paradoxically, is stronger?

Well, their journey has begun.

If you are very fortunate, my friend, it may be that you too will see a butterfly tree, with its thousands of monarchs gathered to roost overnight on their long, long journey south.

A veritable Tree of Souls.