'What time is it?'

It’s great when the clocks go back and there’s an extra hour in bed. But my body still says to me, ‘What time is it really?’.

The shift from British Summer Time to Greenwich Mean Time reminds us how we learnt to measure time.

As a child, I often went with my grandfather to the Greenwich Observatory, where you can stand on line zero. That is one of the meridian lines that go round the earth through the north pole and the south pole, defining time from east to west.

In Greenwich you can have one foot in the east and one in the west.

Before we used online instruments for telling the time, we did it by observation. That’s how we defined the earth as a globe that goes round the sun, sustained by forces we now describe through physical science.

Sun dials still offer us a definitive way to tell the time. In Paternoster Square, next to St Paul’s Cathedral in London, there’s a Noon Mark on the outside of a building. At 12 noon that Mark will also tell you the date and the month.

These days we depend on the internet. But whenever the clocks go back or forward, I’m also reminded of the importance of observation.

I recently visited an exhibition in Rome that showed how St Francis of Assisi realised the importance of the sciences that are built on the power of observation. He was an early environmentalist, 800 years ahead of Richard Attenborough.

St Francis was passionate about creation because it is made by God. He saw beauty in every part of creation, and wanted to know it worked. That religious curiosity inspired the use of perspective in painting and the early exploration of medical science.

The human mind has continued to observe, learn and imagine, even though we are now less good at daring to believe in God as our creator.