But illness does not always write itself upon the body, the sickness I search for is hidden deep within the brain. Sometimes it rises to the surface. Sometimes the face betrays what the body conceals. But there moments, these betrayals, last no longer than an instant. They come, they go, they pass over the patient, darkening and brightening his face like clouds gusting over a meadow. How is it possible, then, to tell what he is suffering when the visible signs of his inner disorder appear so fleetingly upon his face?