Some years ago I looked in the mirror and found my late father staring back at me. Since then, I’ve increasingly enjoyed his company and take counsel from him daily as I shave, hopefully becoming wiser as well as older in the process.

I had to dye my hair last week for a stage play I’m in, and so every time I now glance in the mirror I catch this new stranger looking back at me. No longer am I my white-haired father, but an auburn-haired middle-aged man, if appearance be the thing; which it probably is, given that all the world’s a stage, and all the men and women merely players.

This is the second time this year I’ve had to resort to embellishing my few locks, though it was less traumatic this time round. The first time was in Glasgow some months ago when I also needed to get my eyebrows waxed and tinted, and I found myself outwith my familiar barber’s environment entering the confines of an all-female salon. The fragrance and the conversation were both better. No one talked football. The conversation was all about an Irish wedding that one of the ladies who was getting a perm was preparing for. It was going to be a great occasion.

Within a day or two of dyeing my hair I forgot about my new appearance. My own internal image of myself was as before, so it took a while to understand why friends and acquaintances were walking past me without speaking. They simply did not recognize me. My children’s headmaster finally remarked “Oh, sorry, I thought you were a relative of Angus-Peter’s”. I suppose, in a way, that I was.

To what degree does our appearance shape or define our identity? Who am I, or who are we? Were I to dress as a tramp would I be treated as one? If I put on a kilt, am I immediately branded a Scotsman? To what degree does authority lie in the robe or uniform, rather than in the person hiding beneath the cloak? Is Lord Sewel, for example, still a Lord in his borrowed bra and leather jacket, minus his ermine gown?

"Ye see yon birkie ca’d a lord", as Burns put it ... As a professional actor, you soon learn that two seemingly contradictory truths work together: that nobody is what they appear to be and that you are what you decide to become. Appearances are everything and nothing. As Donald Trump well knows. The Pope, for example, is not the Pope because he dresses up in a white cloak and mitre, but because he is invested with that authority by the church, in the same way that a policewoman’s authority is not in her symbolic uniform, but in the power of law given to her by all of us.

Acting is never pretence. You don’t pretend to be King Lear or Hamlet or Lady Macbeth: you become these individuals; not by dressing in crown and with sceptre, or by growing your hair and beard long and white, but by imbibing into your soul the anguish and pride and hope and despair that leave Lear the tragic figure that he is.

In that sense, appearance is nothing and behaviour is everything. For the rest is mere image. I can pretend to be many things, but unless it’s true, it will ring hollow and folk will instinctively know it’s empty. Our ancient folk consciousness, despite modernity, runs through our DNA and can still detect falsehood a mile away.

This is why rhetoric and action must always match up, for otherwise good people can smell a rat a mile away. There’s no point in preaching devolution or independence for Scotland, for example, while regional power within Scotland continues to wither away on the corrosive vine of increasing centralisation. The Emperor may wear his shining crown, though underneath he is naked.

But like individuals, nations can change; not just their appearance, but their being. Finland should be a prime example for us: there we have a nation that has socially transformed itself from having one of the most depressing health statistics in Europe to being one of the healthiest in Europe. They did it by changing their public policies and collective implementation, not just by dyeing their hair.

The great Michelangelo put it this way: “I saw the angel in the marble and carved until I set him free.” It’s like being at the hairdressers, except with a hammer and chisel: the chisel of art and the hammer of politics.