The king said, look, it’s a lot easier to manage this rabble if we throw a festival from time to time. The thing is, it takes time to organise these things, so all I’m asking is, make it your job to know the signs, and when you’re absolutely certain they’re right, we’ll get the thing happening. Remember, there is a lot of people to move, feed and shelter. Get it right.Imagine how the first astrologer reacted.

The world is full of signs, but they’re not signs of anything until you make them so. Leaves for example, fall off trees for many reasons. Only if nights seem much longer than days and a lot of birds seem to have disappeared, do leaves falling mean it will be cold for a while.

So what is a useful frame of reference? An hour is the time between first light and sunrise, sunset and darkness. It is real, and to say, you’ve got an hour, is to say something meaningful. However, the king wants more lead time than that. The phases of the Moon are real too, but which ones announce the right month?

I can see the astrologer sinking blissfully into a cosmic ocean of interconnectedness, except that his survival is at the king’s pleasure. While he is trying to collate signs such as wind direction, arrival of migratory birds, azimuth of sunrise, amount of rainfall and height of rivers, and intervals of the heliacal rise of familiar stars, he realises something very handy to know, namely that there are 365 days between one heliacal rise of a star and its next.

He has discovered the half-fingerwidth per day revolution of heaven. The king wants next year’s festival a month later? Easy: last full Moon was among the stars of Goat’s Head Soup, the next will be in the Drinks Boy. A degree a day, twenty-nine a month, give or take half a day. We can ensure that the Spring festival is organised for Spring.

Just in case the farmers are wrong and it does rain at a full moon, we can check which month we’re in against the stars rising in the morning. In case we can’t see those either, we can keep records on clay tablets of what we do see and do the maths. If heaven stands still or the Moon falls out of the sky, we’re all dead meat, but in the meantime, we can offer all people a calendar with which they too can learn to read the signs.

Is that what you do with yours?