‘You’ve been feeling tired,’ said the stranger, ‘but I can do something about that. I’ve come to ask whether you’d care to join my Owsla. We shall be glad to have you and you’ll enjoy it. If you’re ready, we might go along now.’

They went out past the young sentry, who paid the visitor no attention. The sun was shining and in spite of the cold there were a few bucks and does at silflay, keeping out of the wind as they nibbled the shoots of spring grass. It seemed to Hazel that he would not be needing his body any more, so he left it lying on the edge of the ditch, but stopped for a moment to watch his rabbits and to try to get used to the extraordinary feeling that strength and speed were flowing inexhaustibly out of him into their sleek young bodies and healthy senses.

‘You needn’t worry about them,’ said his companion. ‘They’ll be all right – and thousands like them. If you’ll come along, I’ll show you what I mean.’

He reached the top of the bank in a single, powerful leap. Hazel followed; and together they slipped away, running easily down through the wood, where the first primroses were beginning to bloom.

I remember reading it as a kid and being profoundly affected by the thought of someone close (as characters in books often become) dying.