NEWPORT BEACH, Calif. - The long dying of Louise Will ended here recently. It was time. At 98, her body was exhausted by disease and strokes. Dementia, that stealthy thief of identity, had bleached her vibrant self almost to indistinctness, like a photograph long exposed to sunlight.

It is said that God gave us memory so we could have roses in winter. Dementia is an ever-deepening advance of wintery whiteness, a protracted paring away of personality. It inflicts on victims the terror of attenuated personhood, challenging philosophic and theological attempts to make death a clean, intelligible and bearable demarcation.