A GOLDEN day for St Luke, one of my heroes. I talk about him at matins to a thin-on-the-ground congregation. Luke, the New Testament's Renaissance man, doctor of body and soul, artist, travel writer - everything. Also the birthday saint of the Greek-English boy who lives up the road, and who, at the moment, is choosing which university to apply to.

It is Luke's "little summer". The garden, while fading, is burning into life. I am reading Colm Tóibín's The Master for the second time, sitting in the garden and nursing the white cat. Ash leaves sail down on us. An unseen farm vehicle clatters behind my wood. The postman bumps down the track. Birds sing as best they can, their soloist fled to Africa.

Among Luke's qualifications, he was a physician of the soul. Think of being able to put this on one's CV. He wrote both his Gospel and the Acts of the Apostles in demotic Greek - the language they spoke in the market-place. But he was astute, taking them to "the most excellent Theophilus", presumably a publisher.

I like to think of Theophilus unravelling them: first, the adventures and words of the Redeemer; then a marvellous traveller's tale as Christ's life and words were sent on their journey.

Luke's biography is plainly written. He never married; he was Paul's young helper; he wrote his Gospel in Greece; and, some believed, he walked to Emmaus with the Lord after the crucifixion for the first holy communion. He - Jesus - would have gone on but for that hospitable "The day is far spent."

"Lighten our darkness," I say. Was Thomas Cranmer referring to the brightness/blackness of the Reformation? Or was he thinking of what Veni, Creator Spiritus describes as "the dullness of our blinded sight"? These questions arise after my having returned from my ten-yearly visit to the optician to have my glasses renewed. The optician is in his twenties. He stares into my eyes with a torch: "Look left, look right, look up, look down. Read as far as you can. Choose your frames."

I feel that he should have complimented me for being able to see at all, let alone see some of his letters. But he is there to give sight, not praise. His own eyes are child-bright. He is reading a very long novel, he says. I know the feeling.

I go to Marks & Spencer's and buy fruit, snowy underwear, a voluminous dressing-gown, and much else. I feel sensible and extravagant. I walk past the wall which the Romans built when St Paul and St Luke were tramping from Antioch. The traffic is climbing round it like insects: the packed school buses, the commuting cars. A medieval church clings to it for dear life.

Flags fly. Students hump homework. A young man takes out a trumpet and his friends fall about laughing. When the music is unexpectedly fine, they lapse into an admiring silence. On the way home, the taxi driver tells me: "You're the first today." I tell him that I am sorry. "Don't be sorry," he says.

I spare him the muddy farmtrack. There are sloes and hips in the tall hedge. The white cat meets me part of the way, not too pleased with my absence. The harvest is sugar beet, the wheat having gone what seems like a lifetime ago. Little streams feed the river - the Stour, which John Constable painted all his life, and mostly in London; for we take our native places with us wherever we land up.

I don't need new spectacles for these old scenes. I peer at the cat through them, and she winks back. I read Tóibín through them. Can he be any brighter?