Other conditions he had to be aware of were rocks that rolled, or pebbles which were thrown at his fire, or any constant noise, and he then had to walk in the direction in which any of these phenomena occurred until the spirit revealed itself. There were many ways in which such a being put a warrior to the test. It might suddenly leap in front of him, in the most horrendous appearance, or it might grab the man from the back and not turn him loose and keep him pinned down for hours. It might also topple a tree on him. Don Juan said that those were truly dangerous forces, and although they could not kill a man hand to hand, they could cause his death by fright, or by actually letting objects fall on him, or by appearing suddenly and causing him to stumble, lose his footing, and go over a precipice. He told me that if I ever found one of those beings under inappropriate circumstances I should never attempt to struggle with it because it would kill me. It would rob my soul. So I should throw myself to the ground and bear it until the morning. "When a man is facing the ally, the giver of secrets, he has to muster up all his courage and grab it before it grabs him, or chase it before it chases him. The chase must be relentless and then comes the struggle. The man must wrestle the spirit to the ground and keep it there until it gives him power." I asked him if these forces had substance, if one could really touch them. I said that the very idea of a "spirit" connoted something ethereal to me. "Don't call them spirits," he said. "Call them allies; call them inexplicable forces." He was silent for a while, then he lay on his back and propped his head on his folded arms. I insisted on knowing if those beings had substance. "You're damn right they have substance," he said after another moment of silence. "When one struggles with them they are solid, but that feeling lasts only a moment. Those beings rely on a man's fear; therefore if the man struggling with one of them is a warrior, the being loses its tension very quickly while the man becomes more vigorous. One can actually absorb the spirit's tension." "What kind of tension is that?" I asked. "Power. When one touches them, they vibrate as if they were ready to rip one apart. But that is only a show. The tension ends when the man maintains his grip." "What happens when they lose their tension? Do they become like air?" "No, they just become flaccid. They still have substance, though. But it is not like anything one has ever touched."