: Actually I'm inclined to believe the proverb that knowledge is power. Can you imagine what you could do with the power to know events before they happen? You could prevent many tragedies from befalling those we hold dear.

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Actually, as soon as you impacted one thing, the entire history would have been changed, and you would no longer be able to have an impact. Or, the impact that you had may in turn, result in several very bad things happening, and a greater tragedy overall.