They come hurrying from a host of twigs, from here, from there, from above, from below; and soon the scattered legion reforms into a group.

The silk thread is something more than a road-making expedient: it is the social bond, the system that keeps the members of the brotherhood indissolubly united.
At the head of every procession, long or short, goes a first caterpillar whom I will call the leader of the march or file, though the word leader, which I use for the want of a better, is a little out of place here.

Nothing, in fact, distinguishes this caterpillar from the others: it just depends upon the order in which they happen to line up; and mere chance brings him to the front.

Among the Processionaries, every captain is an officer of fortune.

The actual leader leads; presently he will be a subaltern, if the line should break up in consequence of some accident and be formed anew in a different order.
His temporary functions give him an attitude of his own.