The Shield of Time Read Online Free PDF

free an agent as you ever were. What mystical powers has it got to constrain your actions that the present doesn’t have? None. You, Wanda Tamberly, could kill your father before he married. Not that you’d want to. But suppose, innocently bumbling around in a year when your parents were young, you did something that kept them from ever meeting each other.”
    “Would I … stop existing?”
    “No. You’d still be there in that year. You’ve mentioned a sister, though.
She
would never be born.”
    “Then where would I have come from?” Impishness flickered: “Hardly from under a cabbage leaf!” and died away.
    “From nowhere. From nothing. Cause-and-effect doesn’t apply. It’s sort of like quantum mechanics, scaled up from the subatomic to the human level.”
    Almost audibly, tension crackled. Everard sought to bleed it off. “Don’t worry,” he said. “Things aren’t that delicately balanced in practice. The continuum is seldom easy to distort. For instance, in the case of you and your parents, your common sense would be a protective factor. Prospective time travelers are pretty carefully screened before they’re allowed to take off unsupervised. And most of what they do makes no long-range difference. Does it matter whether you or I did or did not attend a play at the Globe Theater one of the times when Shakespeare was on stage? Even if, oh, if you did cancel your parents’ marriage and your sister’s life—with all due respect, I don’t think world history would notice. Her husband-who-would-have-been would marry somebody else, and the somebody else would … happen … to be such a person that after a few generations the gene pool would be the same as it would have been anyway. The same famous descendant would be born, several hundred years from now. And so on. Do you follow?”
    “You’re throwing me curve balls till it’s my head that’s spinning. But, oh, I did learn a little about relativity. World lines, our tracks through space-time. They’re like a mesh of tough rubber bands, right? Pull on them, and they’ll try to spring back to their proper, uh, configuration.”
    He whistled softly. “You do catch on fast.”
    She wasn’t relieved in the least. “However, there are events, people, situations where the balance is … unstable. Aren’t there? Like if some well-meaning idiot kept Booth from shooting Lincoln, maybe that’d change everything afterward?”
    He nodded.
    She sat straight, shivering, and gripped her knees. “Don Luis wanted—he wants to get hold of modern weapons—go back to Perú in the sixteenth century and … take charge of the Conquest, then stamp out the Protestants in Europe and drive the Muslims out of Palestine—”
    “You’ve got the idea.”
    Everard leaned farther forward and caught her hands in his. She clung. Hers were cold. “Don’t be afraid, Wanda,” he urged. “Yes, it is terrifying. It could turn out that you and I never had this talk today, that we and our whole world never were, not even a dream in somebody’s sleep. It’s harder to imagine and harder to take than the idea of personal annihilation when we die. How well I know. But it isn’t going to be, Wanda. Castelar is a fluke. By a freak of chance, he got hold of a timecycle and learned how to operate it. Well, he’s one man alone, otherwise ignorant; he barely escaped from here last night; the Patrol is on his trail. We’ll nail him, Wanda, and repair any damage he may have done. That’s whatwe’re for. Our record is pretty damn good, if I do say so myself. And I do.”
    She gulped. “Okay, I believe you, Manse.” He felt warmth begin returning to the fingers between his.
    “Good girl. You’re helping us a lot, you know. Your account of your experience was excellent, full of clues to what he’ll try next. I expect to gather more hints as new questions occur to me. Quite likely you’ll have suggestions of your own.”
    Further reassurance: “That’s why I’m being this