Historical analogies are perilous ventures — high-wire acts of political argument, even in the best of circumstances. A historical analogy that turns on American slavery, though, goes beyond ordinary acrobatics and approaches something like a human cannonball routine.

Last week, The Nation’s Chris Hayes soared through the digital sky with a bold essay that explicitly compares the struggle to curb fossil fuels with the struggle to end American slavery. And miraculously, it works — thanks to the radical implications of the historical formula. To save the planet, what we need are not technical policy adjustments, but a movement that aims at nothing less than the fundamental transformation of America’s political economy.

Yet Hayes has produced a powerful, illuminating beacon and aimed it through the kind of narrow aperture that only a contemporary liberal could have fashioned.