“And, for your safety,” he said earnestly, “imagine now ⁠—and for that matter, imagine always until we leave this place⁠—imagine with the utmost keenness, that you are surrounded by a shell that protects you. Picture yourself inside a protective envelope, and build it up with the most intense imagination you can evoke. Pour the whole force of your thought and will into it. Believe vividly all through this adventure that such a shell, constructed of your thought, will and imagination, surrounds you completely, and that nothing can pierce it to attack.”

He spoke with dramatic conviction, gazing hard at me as though to enforce his meaning, and then moved forward and began to pick his way over the rough, tussocky ground into the wood. And meanwhile, knowing the efficacy of his prescription, I adopted it to the best of my ability.