The introduction to this stunning work is by Murray Rothbard, who calls French radical Gustave de Molinari (1819-1912) the great innovator in the market provision of security. Indeed, he might be regarded as the first proponent of what is called anarcho-capitalism.
Molinari was steeped in the old liberal worldview of Bastiat and hence was a dedicated champion of private property and free markets. But Molinari took matters further to argue that markets were also better at providing the service that the state claimed was its monopoly privilege: the provision of security itself.
His singular contribution, then, was to lead us away from the false assumption of Hobbes that somehow the state was necessary to keep society from devolving into chaos. On the contrary, argued Molinari, the voluntary society is the source of order that comes from freedom itself. There is no contradiction or even tension between liberty and security. If free enterprise works well in one sector, it can work well in other sectors too.
Molinari was indeed a radical but in the sense that foreshadowed the development of American libertarian thought: a radical for capitalism in all areas of life, which is another way of saying that he was a consistent champion of the fully free society.
Perhaps there was a time when people could regard the government monopoly on police and courts as benign, part of the "night watchman" state advocated by the old-time classical liberals. But the march of the police state has changed that: we are more likely to understand that the state's "security" services are the gravest threat to liberty we face.
In that sense, Molinari is the man of the hour.