What goes up, must come down; all politicians are familiar with this iron rule of their profession. And that is the rule which German Chancellor Angela Merkel, the woman who has effectively run Europe for over a decade, is almost certain to be reminded of next year.
She is an instinctively cautious politician. Yet she can also be very courageous.
She joined mainstream politics from East Germany, at a time when few took seriously anyone coming from the former communist east. She made a bid for the leadership of the ruling Christian Democrats at a time when few believed a woman could become a national leader. And as Russian troops intervened in Ukraine in 2014, Dr Merkel brushed aside opposition from her own colleagues and German business interests, and led Europe in imposing economic sanctions on Russia. She may be cautious, but she also knows when to throw caution to the winds.
She is a terrible public speaker, wooden and uncomfortable when facing crowds. But she also attracts fierce loyalty, remains by far the most popular German leader, and is universally known as "mutti", the affectionate German term for mother. The secret of Dr Merkel's success is that she embodies the key virtues of ordinary Germans: seriousness, hard work, disdain for showy gestures and an instinctive caution about experimentation.
Still, Dr Merkel, 63, seems doomed to spend next year just trying to survive at the top. Her party clings to power but, having achieved its lowest score in more than half a century at the general election in September, it is also considerably weakened.
Dr Merkel's decline is usually explained by her decision in 2015 to open Germany's door to a million refugees from the Middle East, a move at that time hailed around the world, but now regarded as a catastrophic political mistake, which alienated millions of voters and contributed to the rise of the populist Alternative for Germany.
The political consensus which governed Germany for decades is breaking down, with voters flocking to smaller parties. But all Dr Merkel is now offering is yet another "grand coalition" with the Social Democrats, her centre-left opponents, equally rejected by the electorate. And her own party is increasingly frustrated by a Chancellor who no longer seems able to feel the nation's pulse and has failed to groom a plausible successor.
Dr Merkel may yet surprise us by reinventing herself. But the chances of that happening remain fairly small. More likely will be a period of stagnation, leading to her departure from the political scene.
For, as her former finance minister Wolfgang Schaeuble put it, the cautious "mutti" has recently been acting like a careless skier, and ended up "unleashing an avalanche".