FORGET the pyramids; ballet is the world's greatest man-made mystery.

How can something that looks so effortless be so gruelling?

Watching our national ballet company execute Highland Fling - and what a compliment for Matthew Bourne, notoriously protective of his oeuvre, to let us borrow it – it's easy to be lulled into a false sense of confidence, of thinking that kind of astounding fluidity is achievable.

It is, as I learn every Monday at 6.30pm, emphatically not. At 6.30pm every Monday I clop to Scottish Ballet HQ to drag myself through a 90-minute class, all the while watching the other women who are more slender, more elegant and more flexible.

It sounds like an hour and a half of self torture and it is, in a way. But with ballet, it's love and there's little choice in love. Knowing this is something you will never perfect or excel at is, oddly, not frustrating but motivational.

I love the etiquette of a ballet class, the routine and discipline. There's a comfort to knowing exactly what will happen next, to carrying out – or trying to carry out – variations of movements that have been performed by others for centuries. There is patience instilled in repeating those movements endlessly, then the joy of their purpose emerging in the choreography of a dance. It's ritual when all around is chaos.

I returned to class after a six-year gap but it's remarkable how the movements live in your muscles. Ballet is a game of opposites; of pain and ecstacy, of delicate strength, of physical lightness and emotional intensity. When it works it is liberating and when it doesn't it is intensely frustrating.

A mute language, it is a system of movement with all the rigours of language's syntax and conjugations but, like language, it is flexible. Ballet is a hard, physical fact but also emotion and expression. It is beauty and logic, maths, philosophy, history.

Memory is key. Ballet has no standardised notation so every performance is a blend of the historical and new. It is an oral history, a passing on of knowledge from one body to another.

As at Highland Fling this week it is a delight, always, to watch the dancers do it properly and sad to glance round the auditorium of the Theatre Royal and see empty seats.

Ballet is, frankly, little short of a miracle. If only more people wanted to unpick its secrets.