He could explains life, but not his own. He wanted to save lives of others, but he failed and even worse, with cost of another's and his own. He proved the truth like this: it's not the it that you want, it's the fantasy of it that you want.
Because in the end, the only way that we can measure the significance of our own lives is by valuing the lives of others. 很Nice的編劇回過頭來再看那場辯論以道出了全部線索——以眼還眼以牙還牙 不得不吐槽一下Winslet跑步的動作好爺們兒啊