This was without a doubt the most important book I've read for a long time now. Its main theme is measuring inequality of wealth and income in as broad a scale as possible (given available data) for the past two centuries, and making observations about it.

As the author himself points out, a lot of economic theory has been based on speculation and poor data, and it is necessary for economists to start looking at the closest we have to the facts, i.e. data of this scale and sort. Piketty describes a few cases where economists' theories were based on very narrow data that was very biased and are immediately proven unsound once one takes a look at the data at a broader level.

The data presented by Piketty is astounding, both in volume and in content. From it arise surprising tidbits, like for example that the percentage of people who inherit more than everyone in the bottom 50% of the income scale will make in their entire lives, is around 15% in France today. Or that the French Revolution didn't impact wealth and income distribution at any significant rate. Or that the income and wealth distribution of today, in some respects is not unlike the one at the beginning of the 20th century (the main difference is the formation of a somewhat more affluent middle class).

Besides presenting the data, Piketty of course presents his conclusions, and then also embarks on a proposal to counteract the "forces of divergence", as he puts it.

His most important conclusion (among many), I think, are that two basic tenets of free market capitalism demonstrably do not correspond to the reality of today and of recent decades. These are that a) the free market organically leads to less and less inequality and b) that capitalism is meritocratic and that everyone has the same resources to succeed.

Finally, Piketty presents his proposal to reduce inequality, and that is to impose a progressive tax on capital, reaching much higher levels than any has reached previously.

One notable feature of this book is that the author seems to assume that equality is something everyone agrees is desirable, or at least that the current inequality is undesirable. I wholeheartedly agree with most of the book's values, this one included, but I also believe that a reason inequality is what it is now, is that a lot of the people involved, do not agree. The book does indeed present its data as impartially as possible, but the commentary and the choice of data itself, is of course replete with the author's ideology of support for equality, and thus I feel that it will fail to convince many free market people who in reality don't have the same values. For the rest of us, I think it is eye opening, thought provoking, and it gives us the ideological fuel to answer free market defenders who try to convince the world that they believe in freedom and justice and so on.