Until she died, my grandmother wrote to me every week. Sometimes, the letters would pile up, and I would take the bundle of blue envelopes and read them all in one sitting. With the carelessness of youth, I never saved them. Now when I come across her handwriting in an inscription in a book, I nearly swoon with love. And guilt.

In fact, I did keep a fragment, the tail end of a letter that I carried around for years, pinning it above desks in three countries. It was a reply to a letter I wrote after being turned down for a scholarship, complaining that life was depressing and maybe I wouldn’t return to university in the fall. I don’t recall the gist of her reply, only the large letters at the bottom of the page: Remember, Depression is cowardice. This was a woman who had lived through the real Depression. Lived through the loss of a farm, a house that burned down, a baby who died of scarlet fever. A woman whose life was based on endurance and hope. Long before I lost the worn piece of paper, her words had become like an old song in my memory. I never uttered them to friends stranded in that wilderness of despair which passeth all understanding, but, for difficult, ordinary depression, her words pushed me out of the door.

Nowadays, the scraps of paper stuck above my desk have telephone numbers for broadband technical support, lists of passwords, scrawled names and dates. And a card from Defra describing ‘bluetongue symptoms to look out for’. It warns that ‘bluetongue affects all ruminants, including sheep, cattle and deer’, that sheep are most severely affected, but cattle act as the main reservoirs of the virus and are the biggest factors in the spread of the disease. The list of symptoms is gruesome, the swollen head of a diseased ewe heartbreaking. I am advised to ‘check livestock twice daily’.

And this I do, taking buckets of extra feed, an apronful of windfalls, treats that make me welcome. We have two breeds. The Shetlands, small and gentle, look like the ‘earth colours’ section on paint charts. Born black, they evolve into taupe, chestnut, dark chocolate. If I sit on the ground, they come up to me, curious, concerned, and if I stay long enough, the older ewes lie down beside me. Then there are the Jacobs, dappled, scatty sheep with attention deficit disorders, courteous but wary.

I cannot claim that these sheep are vital to the financial future of this farm, but they provide a rhythmic sympathy with the earth that justifies everything we do here. They provide the grazing essential to the maintenance of the wildflower meadows, and they give integrity to the menu in our vineyard restaurant. Most of all, they give us joy as we midwife the lambs into the world each spring, as we watch them play lamb games on the ancient oak log that is their favourite playground.

As I write, bluetongue has been found on Suffolk farms, 25 miles from us. A disease once confined to the sub-tropical regions of Africa has arrived here because our warmer winters have enabled the midges which carry the virus to flourish. Morning and evening, I check for signs of swelling and listen to the breathing beneath the symphony of crunching sheep nuts. And I pray for cold and rain. This depression doesn’t feel like cowardice. It feels like the despair that André Gide described when he wrote that ‘melancholy occasionally wins out: man has decidedly botched up the planet’. It is the despair of knowing that last winter was the second warmest on record, and there is no health in it.