I was born in a desert city, Riyadh, nearly fifty years ago. I haven’t been back and know it has changed, but my memories have largely remained intact. In high summer, the sun and heat were almost solid. They were an architecture unto themselves.

Moving between our house and the community pool was an exercise in shadow cat-burglary. You would run from one glimpse of shade to another, stop, reassess, and go again. You simply did not walk through the midday sun. It wasn’t possible, not with the thermal mass of a child. Light, then, was carried upon your shoulders, heavy and foreboding at times; it was a walk to Golgotha. Our childhood stories revolved around heat and shade, swimming as an act of relief and camping in the desert as an act of tribute. Days were organised around sunlight in the then-developing desert town, much as I imagine they had always been for the Bedouin, only with higher stakes then, before oil and money transformed everything.

The light was an architecture which left an impression, then as now.

Sitting here some forty-seven years later, in my studio in Bondi Junction, there is a wintry blue light crawling through an ageing frangipani, its leaves now well composted from their May fall. Not quickly, and probably not naturally, did I learn about light during my professional years after returning from Saudi. Certainly not as a student, nor later as a young architect, where I was taught the primacy of permanence, or of architecture as “a machine for living”. Buildings suffer when they are not resilient, we learn. Architecture requires dependability, we are told.

But it is light which animates.

Light brings with it chance, unpredictability, surprise and change. If it is the role of architecture to resolve practical need, it is the role of light to satisfy our longing for memory, emotion and desire. Beneath its predictability, it is also a benevolent trickster.

What our clients emphasise when briefing us - amenity, views, function - often recedes with time. A house eventually becomes a collection of illuminated moments and memories. The greatest surprises are rarely found in the floor plan, but in the slivers of morning light that quietly settle over the rituals of everyday life.

On Tess and my annual research trip together this year to Mexico, we spent a day at the pyramids. Fabulously these pyramids are organised around a solar and lunar calendar with the pyramids growing each 52 year cycle when the solar and lunar calendars coincided and another layer of stone entombed the last. And yet I catch myself being surprised that the cycles of light could have been so well understood and organised by ancient humans. Is it unbelievable that the solar cycles remain largely unchanged thousands of years later.

The same sun, following the same commute, wakes us and makes our better projects glow with architectural splendour on not just photography day.

Perhaps that is the paradox I love most.

Light is both predictable and not. It is cyclical and momentary. It gives us seasons and takes them away in an instant. It quietly overturns certainty, offers unexpected moments of delight, and animates the permanence of architecture with a life of its own.

We have lived in our home for 16 years, built and altered it several times, and yet I still don’t consider it to be complete. It has changed with each child, with the changing garden, and the death of an old eucalyptus which used to shade us from the sun. It is a story which is continuously rewritten, and continues to be with each changing light.