"Hubbert's views echoed those in The Road to Survival, published the year before, except that he thought in terms of physical limits, rather than biological limits. Still, he ended up in the same place: capitalist-style economic growth was not only unsustainable, it was actively driving humankind beyond its limits to disaster. "The future of our civilization largely depends," he wrote, on whether humanity will be able "to evolve a culture more nearly in conformity with the limitations imposed on us by the basic properties of matter and energy."