what arrives can find the middle by its light.
a radiance has established a center; the field has a middle now, findable from anywhere the light reaches. into that lit field something arrives, and it arrives oriented: the glow tells it where the middle is.
dawn does this for a whole sky, one brightening that gives every traveler the same east. the center was established before the arrival, which is why the arrival lands already knowing where it is.
in plain termssomething new is arriving in a situation that already has a clear middle to steer by.