Please explain this sentence in plain English.
"If reading Piketty reminds us of the troubling inequalities of wealth, reading the recent, pathbreaking OECD report on adult skills in rich countries provides an equally grim picture of the inequalities of knowledge---one that for the United States is terrifying."
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Piketty is the French economist and author of the 700-page book "Capital in the Twenty-First Century"---argues that free markets tend do produce inequalities of wealth that become dynastic and anti-meritocratic.