My favorite medical diagnosis is “failure to thrive.”

Not because patients are failing to thrive — that part makes me sad. But because of the diagnosis’s bold proposition: Humans, in their natural state, are meant to thrive.

My patient, however, was not in his natural state. Cancer had claimed nearly every organ in his body. He’d lost a quarter of his body mass. I worried his ribs would crack under the weight of my stethoscope.

“You know,” he told me the evening I admitted him. “A few years ago, I wouldn’t have cared if I made it. ‘Take me God,’ I would’ve said. ‘What good am I doing here anyway?’ But now you have to save me. Sadie needs me.”

He’d struggled with depression most of his life, he said. Strangely enough, it seemed to him, he was most at peace while caring for his mother when she had Parkinson’s, but she died years ago. Since then, he had felt aimless, without a sense of purpose, until Sadie wandered into his life.