I’m about halfway through Master of the Senate, part three of Robert Caro’s wonderful, epic biography of Lyndon Johnson. Caro’s been writing this biography for more than 30 years, ever since he finished The Power Broker (which itself is one of the best American biographies ever written). The first part came out in 1982, the second in 1990, the third in 2002, and the fourth and final volume, covering Johnson’s vice-presidency and presidency, will supposedly come out in 2012 or 2013, but who knows.

Master of the Senate, covering Johnson’s twelve years as a U.S. senator, is terrific. The first 100 pages are a wonderful capsule history of the United States Senate and tell you everything you need to know about why health care reform has had such a rough time this past year. In part, that’s why I finally decided to start reading the book last month. I’d been meaning to do so for years, and during the week before Christmas I spotted it in a bookstore and decided that given everything going on, now was an appropriate time to pick it up.

As Caro points out, the Senate was meant to be undemocratic. The Framers preached representative government, but they were wary of the masses. The Senate would serve to cool the popular passions and allow for deliberation and debate, unlike the rambunctious House. The Framers accomplished this in part by making the Senate an undemocratically apportioned body, where every state gets two senators no matter how big the state’s population. (This was also a compromise to get the South to hop on board, of course.) They also created a small number of senators, as opposed to the crowded House of Representatives: with only two senators per state, every member of the Senate is important.

And they granted senators six-year terms, longer than presidents or congressmen would get.

And there’s a very important point about those six-year terms: the Constitution provides that those terms are staggered. This is a subtle but powerful characteristic of the Senate that we often forget. Caro quotes a scholar:

It was so arranged that while the House of Representatives would be subject to total overturn every two years, and the Presidency every four, the Senate, as a Senate, could never be repudiated. It was fixed, through the staggered-term principle, so that only a third of the total membership would be up for re-election every two years. It is therefore literally not possible for the voters ever to get at anything approaching a majority of the members of the Institution at any one time.

I think this observation is brilliant.

Grafted onto this original undemocratic structure were certain rules and traditions, such as unlimited debate; its cousin, the filibuster; and seniority. And don’t forget that until the early 20th century, senators were chosen not by the public but by state legislatures. And because we elected a president indirectly through the electoral college, the only body that was directly elected by the people was the House of Representatives.

I read part of Caro’s first book about LBJ, The Path to Power, a few years ago, but for some reason after about 250 pages I put it down and never got back to it. Master of the Senate stands on its own, though; you don’t need to read the first two volumes to get into it, because Caro summarizes Johnson’s life up to then.

Caro on Johnson is alternately exciting and frustrating and maddening. LBJ comes off as a master tactician — you can’t help but be awed by his audacity and brilliance in achieving power — but he also comes off as a Machiavellian asshole who is willing to ruin the careers (and lives) of perfectly innocent men in order to get where he wants to be. I don’t really enjoy reading about people who aren’t likable, so it’s depressing at times. But if you have any interest in 20th century American history, or any interest in politics at all, this is an amazing book.