Change the future.
Because the future would eventually become the past as well.
The future could also begin anew--
Professor Moriarty's voice carried a bewitching quality. "Even if you have nothing to regret right now... can you really rest assured that the future will remain the same? As I said—the Necessary Evil, Premature Death. If the time sent back is reduced infinitely, then it is essentially equivalent to my having done nothing at all; and if the time reversed is infinitely short, that also means nothing was lost.
"As long as you reverse time in time, whenever you come to regret something, no tragedy will ever happen.
"It is just like the insurance those mortals purchase. Insurance cannot prevent accidents from happening; it can only reduce the losses. They cannot stop what has already happened from being changed, nor can they make absolutely certain that something will never happen in the future... But we can.
"Are you really so confident that neither you nor your family and friends will ever encounter any accidents? Do you really believe that your future self will never regret anything?"
"Even if history is torn apart, the only thing we can change is the past of one layer of history... Yet that at least changes the tragedies of the layer of history we inhabit, so we need not accept a future we do not wish to accept. Although this power has already been abandoned by the Reincarnation Angel, it was once wielded by an Angel—especially one of the Equilibrium Path. In other words, this power itself is both reasonable and legitimate."
Professor Moriarty urged him in a low voice, "Or are you saying... that you truly have no fear of the 'unknown' at all?"
"Even if you yourself have no fear whatsoever, when the 'present'