The great advantage of the two-round system is it gives voters the chance to take stock between votes. They can vote for who they want in the first round, and then vote tactically in the second - clear on the likely consequences.
But Le Pen has made the final contest, has a strong protest vote behind her and cannot be counted out.
Early figures show that about a quarter of the conservative vote that supported Nicolas Sarkozy in 2012 split between Macron and Le Pen.
Could Macron be vulnerable to targeted smears or fake news aimed at boosting the National Front's Le Pen?
There are contradictory lessons to be taken from this first round vote.
1 The extremist vote was high
The candidates on the far-right (Le Pen) and on the far-left (Jean-Luc Melenchon) together are projected to have drawn 41.2 per cent of the vote.
2 The traditional party form didn't fare so well
For the first time in modern French history, no mainstream party candidate will contest the final round. A family payment scandal brought Fillon down. Who knows how well he would have done without it? The candidate of the ruling French Socialists, Benoit Hamon, managed only about 6 per cent in a distant fifth place.
3 That suited Macron
Macron was able to present himself as being above left and right factionalism and party politics, appealing to the bloc of independent and swing voters. He is a former Economy Minister for President Francois Hollande's party.
4 There's good and bad news
The democratic centre appears to have held - which is good for stability in Europe - but the slice of the electorate that supports extremist candidates is shown to be huge. That suggests unstable foundations, even if the centrist ultimately gets through.
5 the second round shows the fault-lines
In the end the race has come down to a globalist versus a nationalist - highlighting the fault-lines of politics previously exposed in Brexit and the US presidential election.
That simple fact should prevent anyone from feeling complacent about next month's result.
