Beauty is a difficult thing to explain. What is it? Or more exactly what is it that makes one person beautiful and another not?

If you see someone who is indeed… beautiful, you instinctively know it. It's there in front of you. But explaining what it is that actually makes that person beautiful and the other one not is a much more difficult thing to do.

You can see faces in magazines that are said to be beautiful. They aren't real; their images are airbrushed and manipulated – distortions of a real person. In films, stars can be said to be beautiful, but only with the correct lighting and with perfect makeup.

They aren't real. True beauty can't be seen in two dimensions in magazines or in films. It can only be seen in real life.

Now Katniss was beautiful. There was no doubt about that. She was 5ft 7in – not overly tall, and she was pretty.

Absolutely she was pretty. Again, there was no argument there. But there was more to it than that.

There had to be, but what was it? It's difficult to explain. When you saw her, you wanted to watch her, simply because she was, well… beautiful.

Like an E-type Jag or a barn owl – simply a lovely thing to behold. But it was more than that. You can want to look at something that's pretty – like a bouquet of flowers or a sunset on a cold winter's afternoon, but it doesn't necessarily mean that it's beautiful.

You need something else. And Katniss had it. You couldn't see it, or touch it, or even smell it but you could… sense it.

She had presence. When you saw her, you were compelled to watch her. You had no choice.

It was compulsory. When she walked into the room, people stopped doing whatever it was they were doing. Not just blokes, but girls as well.

It was the most bizarre thing to witness. Once I got used to it, I found it… well… entertaining. It was like watching an electric storm but knowing in advance where the biggest, brightest, loudest forks of lightning were going to land.

People would actually stop talking, reading, writing, anything in fact, just to watch her. It was as if they had been bewitched; as if some strange spell had been cast. It only lasted a few seconds but that's all that was required.

She had entered, and your world was once more in balance. Then everyone carried on as before – but slightly happier. More content that she was now among them.

You were safe, because she was there. Including me, no matter how hard everyone tried to resist it, they found themselves under the same spell. But it was different.

Certainly, he felt the same contentment, the same safety as everyone else, that's true, but there was something in addition. A warmth. That was it – she radiated a warmth to me.

She would smile at me. Even if the room was crowded, she would direct her smile at me. Sometimes even a wink.

I had been blessed. I had something no other boy had. I had her friendship.

Once in Second Year, she appeared late for an Anatomy lecture. Nobody dared do that. It was Dr Saul Weizmann for God's sake.

Absolutely nobody dared do that. Absolutely nobody dared do that and live. For starters, you got a complete telling off there and then in front of everyone.

You were then thrown out of the lecture theatre. And it didn't end there. You were then 'invited' to attend his office, by letter no less, for a discussion as to 'your progress at Edinburgh University's Faculty of Medicine'.

It was a totally withering experience. It had happened to someone two years before. Or was it last year?

It depended on who told the story. Apparently, three years ago someone received a letter and never came back! No one was ever late for Dr Saul Weizmann.

No one. You ran to get there on time. In the rain, in the snow, against the wind. It didn't matter.

You ran as fast as you could. No one was ever late for Dr Saul Weizmann. You would arrive breathless… exhausted… relieved. Excited.

Katniss was late once. They had noticed she wasn't there.

'Where the hell is she?' I had whispered.

A classmate shrugged. 'She's not coming, now. She can just copy our notes later. It'll be fine.'

And then in she came. The door opened and in she came. She turned, closed the door behind her, and in she came.

To say you could hear a pin drop was such a cliché, but that's about how it was. Katniss was about to be executed.

'I'm so sorry I'm late, Dr Weizmann.' And in she came.

'That's alright, Miss Everdeen,' he said (or something like that). He even added, 'I'm glad you've managed to join us.' And he meant it. No sarcasm. He actually meant it. Wow!

Absolutely no one could believe what they had just witnessed. In she came, bold as brass, bewitched the most feared man in their entire world and simply sat down. She looked over to me.

She allowed the tiniest, barely perceptible flicker of her lip to show and she winked. Then she got her folder out. She found her pen, and only then did Dr Saul Weizmann continue.

Now that's beauty.