Isaiah Berlin is one of the greatest modern political philosophers.
This present work was first presented as a series of lectures at Bryn Mawr college in 1952, and later revised. It is an early work containing the seeds of many of his most important ideas, including that of `two liberties'.
It also contains lengthy analysis of the works of those Continental thinkers Condorcet, Helvetius , de Maistre ,Fichte, Rousseau Hegel he learned much from, and made a more vital part of Anglo-philosophical discussion.

Carole Angier writing in the Telegraph describes the crux of Berlin's argument as follows:

"There is a long rationalist tradition, ... stretching from the ancient Greeks through Christianity to the Enlightenment and beyond, in which virtue is knowledge, as Plato said; the world is made in a certain way, by God or nature; and if we understand it rightly we will know our place in it, and what to want.
In different accounts we learn these facts in different ways: from God, nature or science; from the natural light of reason or the uncorrupted heart. But all agree that the world is a natural order, and that real freedom is fitting into that order in the right way. This is what Berlin will call positive liberty, and what he calls here non-humanist or romantic freedom. It is the freedom Rousseau finds in the "general will", which is what our real selves want, and that coincides with the good of society and the will of the ruler. If I obey the ruler, therefore, I really obey myself; and so there is no conflict between liberty and authority, freedom and obedience.
This is the "grotesque and hair-raising paradox", the "sleight of hand" that has, according to Berlin, led to all totalitarian theories and practices since, from Robespierre to Marx, in the name of "higher" freedoms or goods, which the State, or the Church, knows better than my (ordinary) self. Against it he sets Hume's distinction between fact and value, and the modest, "negative" freedom of Mill, which consists of being free from interference by other people."

This work contains the heart of Berlin's analysis of the Romantic Period.It also illustrates how skillful Berlin could be at sympathetically presenting the Utopian schemes of particular Romantic thinkers , while carefully showing his reservations about them.

Like all his works it is written in a sweeping often surprisingly emotional and exhilirating style.

This man makes the 'life of the mind' live.