WASHINGTON — Long before the national press spotlight began to shine on every twist and turn of his life's journey, Senator Obama had this to say about himself: "Junkie. Pothead. 'That's where I'd been headed: the final, fatal role of the young would-be black man. ... I got high [to] push questions of who I was out of my mind." The Democratic senator from Illinois and likely presidential candidate offered the confession in a memoir written 11 years ago, not long after he graduated from law school and well before he contemplated life on the national stage. At the time,...