Elizabeth Edwards lived much of her life knowing all too well what “a matter of life and death” really meant. She knew the best of what life had to offer, and she knew the worst. And she responded to both sides with remarkable grace, dignity and resolve. That spirit likely served her well in the weeks and months leading up to her death Tuesday.

Most Americans met her when she introduced husband John as the Democratic vice-presidential nominee at the party’s national convention in July 2004. The public quickly crowned her the most popular of the two candidates and their spouses — uncommonly warm, funny and down to earth while at the same time savvy on the issues and a top adviser to her husband.

This ability to balance a sense of humor with laser focus on campaign strategy was all the more remarkable given the hell she had walked through since 1996, when the Edwardses’ 16-year-old son died in an auto accident. The tragedy prompted her to quit her job as a lawyer and become a stay-at-home mother to her young teen daughter, Cate. She soon underwent fertility treatments and gave birth to two more children, Emma Claire and Jack.

As the Kerry-Edwards ticket lost in 2004, Elizabeth learned she had breast cancer, a diagnosis she confronted with the same furious tenacity she exhibited in her husband’s campaign. In 2008, not long after John Edwards launched his second bid for the presidency, her cancer returned, incurable this time. Yet she again regained her strength, more intent than ever on drawing attention to her most passionate cause: improving health care.

Horribly, the story grew even more grim, and many of us have to swallow hard at some of the choices Elizabeth Edwards made during this time. Most appallingly, she encouraged her husband to continue to pursue his presidential ambitions, knowing of an extramarital affair that could implode his candidacy. She continued to believe too many of his lies when the rest of the world saw him for the feckless cad he was. Her image also was tarnished by reports in recent years suggesting she often was far harsher with staff members than her public image might indicate.

With some things, Edwards exhibited a remarkable ability to be in denial. But she was not blind to the reality of her cancer — and who cannot admire the example she set of a woman who refused to be a victim to this deadly disease?

Ultimately, she carried that same substance into her fractured marriage and said “enough,” shifting her focus to trying to squeeze a lifetime into the tiny space she had left with her children. Some things, she showed us, simply aren’t worth fighting for. But some things are — and this is the strength of spirit that Elizabeth Edwards will be remembered for.