Hillary Clinton has been a much better senator than Barack Obama. She has been a serious, substantive lawmaker who has worked effectively across party lines. Obama has some accomplishments under his belt, but many of his colleagues believe that he has not bothered to master the intricacies of legislation or the maze of Senate rules. He talks about independence, but he has never quite bucked liberal orthodoxy or party discipline.

If Clinton were running against Obama for Senate, it would be easy to choose between them.

But they are running for president, and the presidency requires a different set of qualities. Presidents are buffeted by sycophancy, criticism and betrayal. They must improvise amid a thousand fluid crises. They’re isolated and also exposed, puffed up on the outside and hollowed out within. With the presidency, character and self-knowledge matter more than even experience. There are reasons to think that, among Democrats, Obama is better prepared for this madness.

Many of the best presidents in U.S. history had their character forged before they entered politics and carried to it a degree of self-possession and tranquillity that was impervious to the Sturm und Drang of White House life.

Obama is an inner-directed man in a profession filled with insecure outer-directed ones. He was forged by the process of discovering his own identity from the scattered facts of his childhood, a process that is described in finely observed detail in “Dreams From My Father.” Once he completed that process, he has been astonishingly constant.