I was eleven, and it was my first year in secondary school.

I don’t remember the day or the date, which in a way surprises me, since everything else was so vivid. But I was walking with Chas, a sometime friend, and we had just finished a maths lesson and were on morning break. The day was overcast, and I suspect it was early summer.

We had just walked down the half dozen steps that ran down to the Lower Quad from the strip of asphalt beside the cloisters which connected the two main school buildings, and separated the Upper Quad from its lower cousin. At that point, I know I had not yet realised that ‘Quad’ was short for ‘Quadrangle’ – why would I? I was in my first year there, all was relatively new and there were more than enough new things to get my head around and cope with, without adding any unnecessary ones into that particular stew.

At the bottom of the steps I looked to my right at the large building that housed the dining hall and the geometry room, among others. There was nothing unusual or special about it that day, I just looked at it and had a powerful realisation – an understanding – that I would never again experience exactly what I was experiencing in that moment.

I might view the same view again, and perhaps the weather would be the same. Maybe even every boy in the school might occupy exactly the same place as they occupied at that moment, either outside where I could see them or elsewhere, unlikely though that might be. But it could never actually be the same again.

The universe would have changed; in one year we would occupy the same position relative to the sun, but not to all the other bodies in space. That would never be repeated. The Virginia Creeper on the dining hall wall would have changed – grown larger, grown new new leaves and lost many of the older ones. So too the other trees and plants.

We would never occupy the same point in time again.

I did not discover anything new that day. I did not add anything to the sum of human knowledge. But what I did was actually experience my existence in a way I had never done before, and have done only a few times since.

It is tempting to look back across that huge gulf – over fifty years, more than half a century – and fill my eleven year old head with profound thoughts that were not there at the time. But I knew I would never experience that moment again, yet I understood instinctively that I would forever be able to recall it. In a way like a snapshot, but a snapshot that included physical feelings and a strange sense of wonder.

Time is sometimes described as an infinite series of moments – because only the present exists – much like an old-fashioned cine film where the perception of movement is supplied by viewing a rapid sequence of still images, each one a gradual progression between the previous ones and the following ones, yet in a way this idea negates the whole concept of motion, since if that really was our experience, we should lose the consequences of motion; just think of the effects of a car crash, or a punch to the jaw, for example.

This was a snapshot in time, but it was anything but frozen. I felt it not only as a moment, but as part of continuous stream. I could still feel the rest of the world flowing past me as I stood there.

Buddhists speak of ‘Little Enlightenments’, which are moments when one has an almost overpowering feeling of existence, a strong sense of being connected to the whole world, during which that person experiences a heightened awareness – they seem to hear what is around them more clearly, see unusual detail and find that even colours appear more vivid than usual. At the same time thought seems unusually profound. This only lasts a short time, perhaps a couple of seconds, but leaves behind a powerful impression. I have twice experienced this, and each time I was somehow reminded of my experience that day at school.

And I wonder if the connection there is that I had an unexpected understanding of time for a few moments at the foot of the steps below the cloister.