You will not have known William. He was a tall, elderly Bristolian with wavy grey hair swept back from his forehead.

He had a gentle smile, a soft voice, and was warmly at ease in his apartment. His wife Maisie was a short, bustling woman with a happy knack of being able to produce warm scones, cream, jam, and a cup of tea whenever I visited them.

In retirement, William spent much time in a deep chintz-covered armchair, placed so he could look out over the small garden and watch people walking past on the pavement. He was the picture of wise contentment.

Yet his slippers gave his secret away. As winter drew on each year, he would ease his feet into cosy, cloth-covered slippers, and remain seated even when women entered the room.

For such a naturally courteous, old-fashioned gentleman, this was surprising.

He would apologise for not getting up but with a wave of his hand would encourage visitors to sit down so he and they could talk.

He wore slippers not for reasons of fastidious tidiness, but because in the First World War he had suffered terrible frostbite in the Flanders trenches, and every winter, when the temperature dropped, the painful damage would return to plague him.

And yet not once did I hear him complain. Not once was there any self-pity. Not once was there any bitterness about the nightmares he had lived through in that terrible war.

The ability to forgive is a gracious mercy. It requires an act of will, a deep awareness that all of us require forgiveness, and all of us need to learn to forgive.

Without it, we fail to become the people we could be, and true contentment eludes us.

Now, where are your slippers?

The Herald’s ‘I Say’ column is written by former vicar of The Bourne and author, Bishop Christopher Herbert