Save for his mother, no one in Barack Obama’s life was more influential in shaping his character than his grandmother, Madelyn Dunham, known affectionately among the family as "Toot."

"I suppose I provided stability in his life," Madelyn told me matter-of-factly in her Honolulu apartment in October 2004, one of only two media interviews, by my count, that she has given.

But Toot (short for "Tutu," the Hawaiian moniker for grandmother) provided much more than down-to-earth care to Obama. She imbued in him a view of human nature that was both pragmatic and idealistic. And perhaps most important, Dunham offered him an in-house example that what comes out of someone’s mouth is not always what is in one’s heart, especially involving matters of race.

The Democratic nominee for president is leaving the campaign trail today for a two-day visit with his 85-year-old grandmother in Hawaii. She has been ailing for some time, and although she is out of the hospital, media reports speculate that she is near death. Obama once told me that his life’s greatest regret was not being present at his mother’s bedside in her final hours. He apparently doesn’t want to live with the same regret involving his grandmother, who was Obama’s primary caregiver as his mother traveled to Asia and Africa for her studies as a cultural anthropologist.

Madelyn Dunham, a woman with a no-frills, no-nonsense Midwestern sensibility, instilled in her grandson the pragmatic streak that can offset the dreamy romantic side of his character, which he picked up from his liberal, sensitive mother. While Obama’s mother instantly saw good in nearly everyone, Dunham was far more circumspect. She knew how to size up someone pretty quickly—a trait that Obama would later find in his wife Michelle. Tough, straightforward, and hard-working, Dunham rose from being a secretary at a Honolulu bank to retiring as the bank’s vice president. It’s that kind of resolve and moxie, I am convinced, that helped Obama muster the drive to run for president.

When I met Dunham in 2004, she was 82 and her health was failing her even then. She walked with an accentuated stoop and appeared depleted of energy. But her mind was clear and taut, and she mulled her words carefully, just like her grandson. She sat with a reporter for the Chicago Tribune not because she liked to hear herself talk, but out of obligation to Obama, who was then running for the U.S. Senate in Illinois.

Dunham was loath to talk about the inner workings of her family, which had endured out-of-wedlock pregnancy, divorce, and alcoholism. Still, she offered many insights into Obama’s development. Though she tried, she could not hide her disdain for Obama’s father, who abandoned his wife and toddler and then failed to keep promises of faraway assistance. She called Barack Sr.  "straaaaange," lingering on the "a" for some time.

She shocked me when she said that she did not "trust everything that foreigners say," a reference to his father’s failings, but a statement that also condemned the vast majority of the world’s population. It struck me as antithetical to Obama’s "we are all one people" vision of the universe.

But perhaps most crucial, his grandmother forced Obama to reconcile the complexities of race relations and human behavior. She was a white woman who occasionally espoused negative feelings and showed outward fear toward minorities. Yet, she loved a little African-American boy so dearly that she would make great sacrifices in her own life for the sake of his. Even this tough lady’s heart was big, Obama learned.

Dunham sacrificed for Obama and his sister Maya, raising the family in a modest two-bedroom apartment, forsaking a house and material possessions in order to have money to send Obama to an elite preparatory school. In this respect, she offered a living example of his mother’s philosophy that, at our core, human beings are compassionate and good, despite the harsh words we might issue toward each other.

Obama spoke publicly about these matters in his speech on race in Philadelphia, delivered as the Rev. Jeremiah Wright episode threatened to destroy his candidacy. "I can no more disown [Rev. Wright] than I can my white grandmother—a woman who helped raise me, a woman who sacrificed again and again for me, a woman who loves me as much as she loves anything in this world, but a woman who once confessed her fear of black men who passed by her on the street, and who on more than one occasion has uttered racial or ethnic stereotypes that made me cringe."

I’m not sure how difficult it was for Obama to speak about his grandmother and her prejudices. But given her pragmatism, I’m sure that if she was consulted, Dunham would have told him to go right ahead—if that’s what it took to get the job done.