Gianno Pilo, now Mr Berlusconi's full-time opinion poll wizard, first came to him last year, before the now Prime Minister had publicly announced his intention to go into politics. Mr Pilo told him he had some polls that showed that 'you can be prime minister if you want'.
Mr Pilo now conducts three polls a day for Mr Berlusconi; on the basis of the results, Mr Berlusconi makes his decisions. As one insider put it: 'Berlusconi brought America to Italy, for good and bad. He has a burning desire to please his public, a Clintonian syndrome.'
The polls, the results of which are often kept secret, can sometimes show the most unexpected trends. For instance, before Mr Berlusconi took his astonishing decision to fire the board of the RAI state broadcasting corporation, Mr Pilo made a few soundings. 'And he found that most of the Italian public actually hates the guts of RAI,' said one source.
At this summit, Mr Pilo will be watching closely how Mr Berlusconi's performance as a world leader plays with his public. The other summiteers will probably help him a great deal. None of them has displayed overmuch concern at, say, the presence of neo-Fascists in his government.
Two leaders have already helped him at the highest possible level. President Clinton, by making Mr Berlusconi's Italy his first pitstop on his first trip to Europe last month. Chancellor Kohl, by being the first leader to invite Mr Berlusconi to his country for a bilateral summit.
'It was Berlusconi who asked for it; he really wanted to come,' said a German official. 'So we agreed to invite him. If you are about to assume the presidency of the EU, you take the chance to build up relations with any new leader.' Mr Berlusconi already had strong links with Bonn; as a businessman, he did many deals in Germany.
On the other hand, the supposed Anglo-Italian alliance which Britain hopes will help it defeat the Franco-German axis is, as a consequence, looking shaky at this summit. British diplomats are pinning their hopes on Mr Berlusconi's Foreign Minister, Antonio Martino, a disciple of Milton Friedman who visited London last week; and on Mr Martino's deputy, Livio Caputo. As deputy editor of Il Giornale, one of Mr Berlusconi's newspapers, Mr Caputo was famed for his modern-day Gabriele d'Annunzio-style campaign to assert Italian property rights in Slovenia and Croatia. As one Rome insider put it, 'They really represent the driest right you can think of.'
AS FOR Mr Kohl, he is busy thinking of ways to make the Eastern Europeans abandon their ambitions to enter the EU in the near future without offending them; that means a new concept for economic aid. A subject dear to his heart at this summit is an aid package on nuclear safety in the former Soviet Union. Closing down Chernobyl will come first, of course.
But the nuclear safety package, if successful, will be Germany's model for a whole new way of assisting Eastern Europe through concrete programmes, rather than throwing money at them. One German analyst noted: 'I mean, let's face it, most of the money we have given to Eastern Europe since the end of the Cold War is now in bank safes in Switzerland.'