When humans began to decipher the language of trees, pheromones in the air and electrical signals in the dirt, it was mostly warnings and greetings to one other. They were slow conversations that took many years to finish. A decade passed before humans learned to make the signals themselves and began to talk to the trees.

The scientists asked them about the weather—a highly popular topic—and animal migrations and soil quality. However, one enterprising intern asked: “What do you fear?”

The trees were quiet for a long moment as if thinking. Trees are slow to talk, and even slower to think. The tree gave a reply on a cool fall day: “Ghosts,” it said, “ghosts.”

Scientists took this as a sophisticated reply and started to ponder the meaning of “ghosts.” Was it a metaphor? Were they mistranslating? Did the trees have spiritual practice beyond their comprehension?

But talking to trees is not the same as understanding them. The scientist wondered if trees too scented phantom pheromones in the air of those long passed or felt electrical signals from tree stumps that no longer had living roots. They wondered if it was not just humans that have souls, but if the entire planet was covered by forests you cannot see and haunted by plants that no longer grow.