Not the horror of religious extremism and hatred that seems to be flooding our world at the moment.
Nor the current epidemic of killing, bombing and terrorising.
They create an unavoidable ever-present whisper of fear that we are all trying to ignore.
They are all too huge somehow, too terrible, too incomprehensibly inhuman to think about.
But this week something happened, something small and tangible and utterly unsettling.
It started with the milk.
Three times a week we have our milk delivered by a milkman ( a quaint English habit that we can't quite kick}.
On Monday, Wednesday and Friday, we wake up and our milk is waiting for us on the doorstep.
But last week,it wasn't.
I opened the door to a frayed doormat and an empty space where the milk bottles should have been.
Outraged we phoned the dairy who apologised, explained it was probably a new milkman who hadn't quite learnt his round yet and gave us a refund.
But it wasn't the milkman.
On Saturday we found our milk bottles, and even some that belonged to our neighbours.
It was the evening, already full of November darkness, and Ninesh (my husband) and I, were piling bedding into our camper van.
We were spending the night with my sister and her family because my niece was having an 18th birthday party and, much to our surprise, she had invited us "oldies," as well as our teenage children.
But since we are at the age where the thought of sleeping on the cold floor amongst empty beer cans and smouldering cigarette butts fills us with horror, we'd decided we would sleep in the relative comfort and splendid isolation of our van.
Cursing under his breath, he turned on the lights..... it wasn't just milk bottles.
The roof bed had been pulled out and covered in a now-grubby sheet.
One of our torches lay on top of it and every surface was covered in a thin film of tobacco dust, cigarette ends and joints.
At first Ninesh and I just stood there, speechless.
How could it be that a few yards from our front door, a complete stranger had been living in our camper van?
How many times had we walked past and not noticed him?
How many times had he watched us enter and leave our house?
How many times had he watched the living room window as the daily mundanity of our family life unfolded?
How many times, under cover of early-evening and late-morning darkness had he climbed in and out of our van?
And how had we not heard the door sliding shut? ( We never manage to do that without waking everyone up!)
We felt shocked, violated, indignant.
How dare he...
We started looking around more closely.
Opening cupboards, pulling out drawers, checking for more evidence, wondering what he had stolen.
But the truth was, he hadn't stolen anything.
Instead, he had left his phone charger, his pen knife and his grinder lying around.
One of our neighbours wandered over
" Has someone been living in your van?" he asked, peering through the door.
" How did you know," asked Ninesh.
" Oh, we just saw a young man wearing a hoodie leaving it," he said." It was only about 5 minutes ok. Shall I help you chase after him. I know which direction he went in?"
For a moment I followed his gaze through the street-lamp lit darkness.
Then I turned and looked at the penknife and the phone charger and the grinder, probably everything he owned in the world.
I looked at the crumpled sheet and the lonely torch.
" It's ok," I said.
" But he broke into your van and lived in it," said our neighbour.
" But he's gone now," said Ninesh " and he didn't steal anything and we're taking the van away tonight."
And suddenly I imagined it.
A young, homeless man turning the corner onto our road late that night, and staring at the space, where his temporary home should have been.
And just like that my sense of indignation and violation evaporated.
And all I felt was a sense of overwhelming sadness.
We cleared away the milk bottles and the cigarette ends.
We opened all the doors and windows to get rid of the smell of cigarette smoke.
I collected the sheet and put it in the washing machine and we folded away the roof bed.
In the end all that was left of our van's temporary inhabitant was a small pile of his possessions.
We drove to the party, trying to process what had just happened and not to notice the scent of tobacco that lingered in the air.
" I feel bad keeping his stuff," I said, " it's probably all he's got. What shall we do with it? Shall we just leave on our wall and hope he comes by to pick it up?"
" Good plan," said Ninesh, " we'll just leave a phone charger and a sharp knife outside our house! No one else would be interested in those!"
" Perhaps we could leave a note," I suggested.
" Right," said Ninesh, " to the person who broke into our camper van and has been living there illegally-
Please knock on the door and we will return your possessions!"
I sighed, he was right.
The price he had paid for living in our empty camper van was the loss of everything he owned.
" At least he still has his phone," Ninesh pointed out.
I thought about that.
Wondered how someone who has nothing can afford a phone.
Wondered why you would choose a phone over food.
There is a cynical explanation, that the phone was stolen that he was dealing drugs, that he needed to stay in touch with his contacts.
And I know that's the most likely answer.
But a part of me wants to believe something different.
I want to believe that at least, with a phone, he could pretend he wasn't lonely.
We danced the night away amongst devils and angels at my niece's " Gods and Monsters," party and when the night was over we climbed wearily into our van.
We reclaimed it as our own. as the movable holiday home it is.
But emotions are never that simple.
He haunted our dreams, this homeless man.
It's easier not to face the truth, to hide behind our belief that we are, at heart good people who give money to charity and believe in freedom and justice and equality.
But perhaps believing is no longer enough.
Because there is something so undeniably unjust and unequal about living in a world where some of us have empty bedrooms and empty vans and food to spare while all around us our world is filling with people who have nowhere to sleep and nothing to eat.
So now our lives have been divided into the time before our stranger in the camper van story and the time after it.
Before it happened I could convince myself that " just caring ,"was enough.
Since it's happened my illusions of personal goodness have been shattered.
I phoned and registered our spare room as a space for asylum seekers with the council but apparently Chichester is not one of the places they are fleeing to.
Perhaps we should leave our van door permanently open and a supply of food and milk inside.... but somehow we can't bring ourselves to be that altruistic.
In this world of constant change and fear, it's hard not to cling even more tightly to what you hold dear.
I find myself looking searchingly at " The Big Issue," sellers and the empty-eyed hooded figures slumped on benches.
" Is it you?" I want to ask them," did you sleep in our van?"
But I know I never will.
The truth is, I don't have the courage to cross the bridge from thought to action.
And so I live with the knowledge that our camper van will never feel quite like ours again. That staying in it will always make us feel just a little bit guilty.
And every time I lie down on its comfortable cushions, I will see the lost face of a complete stranger who, for a very short time, had a place that he could call home.
