If Tóng Rén has appeared in your reading, the book is naming a fellowship built on shared substance rather than shared surface. The single yin line in the second place is met by five yang lines — many, yet ordered around one principle. The image is bright fire under open sky, visible from a distance.

Classical commentary reads this hexagram as the formation of community over a real cause. The qualification 于野 — in the open country — is the key. Fellowship behind walls is partisanship; fellowship in the open is the kind that can carry weight. The hexagram appears when the question is whether to commit to a shared undertaking, and whether the sharing is honest enough to bear the commitment.

What the book counsels is the clarifying work that comes before the joining. 類族辨物, sort kinds, distinguish things. Know which alliances are based on what they appear to be based on. Know who is in the circle because they care about the cause and who is in it for proximity. This is not cynicism; it is the work that lets the fellowship survive its first hardship.

Tóng Rén's strength is large enough that 利涉大川 — crossing the great river is favoured. The book is rare about such permissions. The hexagram appears when collective action is genuinely possible. The failure mode is to mistake the warmth of agreement for the depth of it, and to ride that warmth into a venture that the actual fellowship cannot carry.