“The supreme secret we kept from you was our purpose in coming to Earth — that purpose about which you have speculated so endlessly. We could not tell you until now, for the secret was not ours to reveal.
“A century ago we came to your world and saved you from self-destruction. I do not believe that anyone would deny that fact-but what that self~destruction was, you never guessed.
“Because we banned nuclear weapons and all the other deadly toys you were accumulating in your armouries, the danger of physical annihilation was removed. You thought that was the only danger. We wanted you to believe that, but it was never true. The greatest danger that confronted you was of a different character altogether — and it did not concern your race alone.
“Many worlds have come to the crossroads of nuclear power, have avoided disaster, have gone on to build peaceful and happy civilizations — and have then been utterly destroyed by forces of which they knew nothing. In the twentieth century, you first began to tamper seriously with those forces. That was why it became necessary to act.
“All through that century, the human race was drawing slowly nearer to the abyss-never even suspecting its existence. Across that abyss, there is only one bridge. Few races, unaided, have ever found it. Some have turned back while there was still time, avoiding both the danger and the achievement. Their worlds have become Elysian islands of effortless content, playing no further part in the story of the universe. That would never have been your fate or your fortune. Your race was too vital for that. It would have plunged into ruin and taken others with it, for you would never have found the bridge.
“I am afraid that almost all I have to say now must be by means of such analogies. You have no words, no conceptions, for many of the things I wish to tell you — and our own knowledge of them is also sadly imperfect.
“To understand, you must go back into the past and recover much that your ancestors would have found familiar, but which you have forgotten — which, in fact, we deliberately helped you to forget. For all our sojourn here has been based on a vast deception, a concealment of truth which you were not ready to face.
“In the centuries before our coming, your scientists uncovered the secrets of the physical world and led you from the energy of steam to the energy of the atom. You had put superstition behind you: Science was the only real religion of mankind. It was the gift of the western minority to the remainder of mankind, and it had destroyed all other faiths. Those that still existed when we came were already dying. Science, it was felt, could explain everything: there were no forces which did not come within its scope, no events for which it could not ultimately account. The origin of the universe might be forever unknown, but all that had happened after obeyed the laws of physics.
“Yet your mystics, though they were lost in their own delusions, had seen part of the truth. There are powers of the mind, and powers beyond the mind, which your science could never have brought within its framework without shattering it entirely. All down the ages there have been countless reports of strange phenomena — poltergeists, telepathy, precognition — which you had named but never explained. At first Science ignored them, even denied their existence, despite the testimony of five thousand years. But they exist and if it is to be complete any theory of the universe must account for them.
“During the first half of the twentieth century, a few of your scientists began to investigate these matters. They did not know it,but they were tampering with the lock of Pandora’s box. The forces they might have unleashed transcended any perils that the atom could have brought. For the physicists could only have ruined the Earth: the paraphysicists could have spread havoc to the stars.
“That could not be allowed. I cannot explain the full nature of the threat you represented. It would not have been a threat to us, and therefore we do not comprehend it. Let us say that you might have become a telepathic cancer, a malignant mentality which in its inevitable dissolution would have poisoned other and greater minds.
“And so we came — we were sent — to Earth. We interrupted your development on every cultural level, but in particular we checked all serious work on paranormal phenomena. I am well aware of the fact that we have also inhibited, by the contrast between our civilizations, all other forms of creative achievement as well. But that was a secondary effect, and it is of no Importance.
“Now I must tell you something which you may find very surprising, perhaps almost incredible. All these potentialities, all these latent powers — we do not possess them, nor do we understand them. Our intellects are far more powerful than yours, but there is something in your minds that has always eluded us. Ever since we came to Earth we have been studying you; we have learned a great deal, and will learn more, yet I doubt if we shall discover all the truth.
“Our races have much in common — that is why we were chosen for this task. But in other respects, we represent the ends of two different evolutions. Our minds have reached the end of their development. So, in their present form, have yours. Yet you can make the jump to the next stage, and therein lies the difference between us. Our potentialities are exhausted, but yours are still untapped. They are linked, in ways we do not understand, with the powers I have mentioned — the powers that are now awakening on your world.”
— Arthur C. Clarke