You don't hear her interested hum as sound; you feel it as a change in the air - the invisible spark of inspiration that turns the herd.

Horses are things of river and ocean; this is known - but water cannot turn like this. This many bodies, panting breath, flesh and force and power enough to grind boulders to dust and churn this endless grassland into rasputa mud. And they turn. They wheel. The direction of the river changes. 

They thunder closer. Not close enough to touch, not close enough to feel their breath, but close enough that you can hear the earth tear beneath their hooves, hear teeth snap, hear the water splash as they gallop across shallow lakes so fast that you can imagine them running over the top of it. They run past you, a fleeting moment in an eternal vista. A long straight line and then a sharp turn, running straight until they enter a gentle curve, another sharp turn, another gentle curve, and then rejoining the flow to form this almost circle around you. You are at the center of an equine whirlwind. The shape that they make with their course almost perceptible through the storm of them. If only you could see, could see from a little bit higher and it would all be clear...