“The sun shines not on us but in us.”  These words, on Helensburgh’s waterfront, mark one end of the John Muir Way.  On other days they would be a reassuring piece of spiritual wisdom.  Today I am not so sure.  As we mount our bikes, to set off on the first section of the 134 miles of coast-to-coast trail, I scan the sky.  The forecast is reasonable but it feels as if Muir’s wisdom is born of bitter experience – that in Scotland the only kind of sun that does shine is often the inner one.

Cycling and I parted company some decades ago and we are only now getting back on nodding terms.  So, after struggling up the early, and already far too steep, hills, I whizz with child-like glee down the descents – reaping the gain for the pain.  As the route levels out, I am transported back to school days when cycling felt just as care (and car) free as it does along these gentle, joyous lanes.  The flower-festooned verges and hedgerows also hark back to an era when such bio-diversity had not been widely sacrificed to the gods of industrial farming.

John Muir would have had something to say about that.  In 1849, as a ten year-old boy, he made this journey (in the opposite direction) from his family home in Dunbar to sail from Helensburgh for a new life in the USA.  As an adult, he would champion the radical idea of the conservation of nature and become the founding father of the American National Parks.

After lunch, our route merges, firstly with the West Highland Way – on which we inch forward against a tide of European hikers making for the west coast (haven’t they heard of Brexit?) – and then with the Thomas Muir Way (no relation).  Now, for several miles, we are invited to reflect on a radical political reformer, who established a Scotland-wide network of clubs inspired by the principles of the French Revolution.  Following his support for a united Ireland, Thomas became a fugitive from justice, before eventually being transported to Australia.  How things have changed – today he has his own long-distant path.

This is now the third trail we have travelled along dedicated to a great Scot.  Last summer, Jenny and I found ourselves on the James Hutton Walk, along the Berwickshire coast.  Here we were treated to “Hutton’s unconformity” – strangely folded rocks which helped this pioneering geologist to demonstrate deep geological time, transforming our understanding of the age of the earth.

Since moving north of the border, I have been struck by the way Scotland honours its intellectual heritage.  More than once, I have heard it said that everything worth inventing was invented by a Scot.  Even this streak of nationalistic hubris makes the point.  Whereas the statues of London so often celebrate the political and military leaders of imperial Britain, Scotland’s capital heralds its writers (Walter Scot), philosophers (David Hume) town planners and environmentalists (Patrick Geddes) explorers (David Livingstone) physicists (James Clerk Maxwell) and philathropists (Catherine Sinclair) – and many more.

And often these figures were not narrow specialists but great polymaths.  Is there a connection here with an education system that still does its best to preserve space for a broad, interconnected syllabus?  As we reach a weary journey’s end, some other words of John Muir return to me.  They were etched in a circle of stone back at the start of the day.  “When we try to pick out anything by itself, we find it hitched to everything else in the universe.”