It said how much he'd liked staying with us, and it enclosed a piece of paper that puzzled us for some time.
There was nothing written on it, just a black, photocopied - well, blackness, relieved by lots of white sploshes and dots, some running into each other, where the original document was obviously getting a bit past it.
Or so I thought.
But after a long time - several hours or days, I don't recall sixteen years on - the light suddenly came on behind the In-Charge's eyes. He didn't exactly shout 'Eureka!' but it was something along those lines.
'It's Europe,' he said. 'At night.'
And then it all made sense.
The sploshes were the huge centres of population, the connecting white areas the busiest parts of each country.
Needless to say, our own wild west coast of Ireland was unrelieved black.
I wonder if it would still be black on a similar image today?
I think, compared with most of Europe, it wouldn't be too bad.
One of the benefits of living in - basically - the middle of nowhere, is that our night sky is choc-a-bloc with stars. They don't have to fight to be seen here. They are overwhelmingly bright and fantastically numerous. The Milky Way is a pale, gauzy scarf stirred through the heavens, Orion marches all around us, sword at the ready, the Plough looks permanently on the boil (it appears to my unscientific gaze more like the porridge pan than anything else) and the morning and evening stars are as bright as the moon. From the hills - even from the sea - you can, if you're lucky, see the Aurora Borealis at certain times of the year. You can watch the satellite stations Big Brothering us. You could lie in the garden and identify every constellation in the Northern Hemisphere, if you felt so inclined.
But drive a few miles along the coast and there is an orange haze in the sky over Sligo Town - just a reminder that in the real world total darkness is a thing of the past, and Sligo is just a village compared with most of the world's cities.
As I am writing this, the lights have just gone out! How ironic.
|Fortunately the candles are never far away|
Well, our powercut lasted for an hour, but it was about 26 hours too soon.
Tomorrow is Earth Hour, and - as in years gone by - we will turn everything off for an hour, starting at 8.30pm local time, lighting our numerous candles instead.
In the six years since it started, Earth Hour has grown and grown, and now involves 'hundreds of millions of people across 7001 cities and towns in 152 countries and territories'. (Taken from the official website.)
Which is fantastic.
But it's all well and good turning the lights off for an hour, welcoming, for once, the darkness - but what about after the hour? Do we just go back and flick it all on again?
Will anything have changed?
Hopefully. But only if we all join in, talk about it, and maybe turn off the lights an hour every month, every week, every day. Changes start with small things, after all.
Have a look at the challenges on the website. Maybe you can commit to taking up one or two, or starting your own.
I don't know what I will do for mine, I'll have to think about it while the lights are off.
One thing is certain, if we don't face up to some of the real challenges facing this planet that we call home, there won't be any need for an annual moment called Earth Hour, because the earth won't be here anymore.
For some reason I can't upload the YouTube Earth Hour video, but you can find it by clicking on this link: