Thou shalt not' is soon forgotten, but 'Once upon a time' lasts forever. - Philip Pullman

Everything means something.

And at the word alone, Will felt a great wave of rage and despair moving outwards from a place deep within him, as if his mind were an ocean that some profound convulsion had disturbed. All his life he'd been alone, and now he must be alone again, and this infinitely precious blessing that had come to him must be taken away almost at once.He felt the wave build higher and steeper to darken the sky, he felt the crest tremble and begin to spill, he felt the great mass crashing down with the whole weight of the ocean behind it against the iron-bound coast of what had to be. And he felt himself crying aloud with more anger and pain than he had ever felt in his life, and he found Lyra just as helpless in his arms. But as the wave expended its force and the waters withdrew, the bleak rocks remained; there was no arguing with fate; neither his despair nor Lyra's had moved them a single inch.

When you choose one way out of many, all the ways you don't take are snuffed out like candles, as if they'd never existed.