<em>Illustration: michaelmucci.com</em>

Illustration: michaelmucci.com

If this is the time when people sit back and relax and, hopefully, even read, spare a thought for the greatest biography ever written, a commanding work of research, insight and narrative power which sheds light on why, on both sides of the Pacific and both sides of the Atlantic, politics is currently at such a low ebb and debt is at such a high tide.

The Passage of Power, by Robert Caro, the fourth volume of a 3000-page masterpiece collectively called The Years of Lyndon Johnson, was released this year and such is its command of the workings of politics that it illuminates why America is on the brink of what has become known as ''the fiscal cliff''.

Reading the greatest political biography ever written unlocks the labyrinth of congressional politics, the bias towards stasis, the in-built self-interests, the regional jealousies, the personal fiefdoms and the immense power of the special interest lobbies.

''The fiscal cliff'' is just another term for fiscal discipline, imposed on a system which is racing spectacularly towards an unsustainable social security system, with a structural inability to curb bad habits. The next generation is being robbed by the greediest generation in American history.

All this can be understood by reading Caro, because the last person who was able to overcome the stasis in Washington was President Lyndon Johnson. Caro explains how and why in pleasurable detail.

In so doing, he has produced the most sweeping historical tour de force since Edward Gibbon's The History of the Decline and Fall of the Roman Empire, first published in six volumes between 1776 to 1788. It took Gibbon 22 years to write his 3000 pages. It has taken Caro 38 years and he is not finished. He has worked on his project since 1974, the year after Johnson died.

Caro was a young journalist when he embarked on this. He is now 77, and still going to the office every weekday, still being assisted by his wife, and still working on volume five.

In the introduction of the first volume, published in 1982, Caro referred to a ''three-volume work''. This year saw volume four, 700 pages, and it ends early in Johnson's presidency, with much to come.

The Years of Lyndon Johnson is more than a superb synthesis of half a century of American politics. The fourth volume also seeks, in Caro's words, ''to explore … what lay beneath power's trappings at power's core''.

At the outset, in 1982, he wrote: ''The rise of Lyndon Johnson sheds light on the new economic forces that surged out of the south-west in the middle of the 20th century, on the immense influence exerted over America's politics [by] … the oil, gas, defence, space and other industries of the south-west - that raised him to power, and once he was in power, helped him to extend it. They placed at his disposal sums of money whose dimension was extraordinary in politics.''

The pattern continues to this day.

Caro clearly loathes Johnson but his loathing is mixed, in good measure, with awe at Johnson's achievements, his energy, his will to power, and the sheer vivacity of his character. History is not written by the good and the bland. It is written, disproportionately, by ruthless egoists.

Volume four dwells on Johnson's despair at losing the power he had acquired over years in the Senate, then gave up for an empty vice-presidency. He was stripped of power by the Kennedy inner circle and openly despised by the president's younger brother, Bobby.

Suddenly, on November 22, 1963, President Kennedy was obliterated by an assassin.

Caro's coverage of that day and its aftermath is superior to any that has gone before, and there have been many. He also takes the measure of the fallen president and finds him wanting: ''For all John F. Kennedy's remarkable … eloquence … few of his domestic goals that required legislation had been turned into reality, and at the time of his death, every major Administration bill that was before Congress was stalled.''

The parallel between Kennedy's legislative achievements and those of the current US President is striking. The White House has another occupant who is charismatic but came to power with zero executive experience, who proved to be brilliant at campaigning but not governing. The ''fiscal cliff'' represents a real risk to President Barack Obama. His legacy in government could be shadowed by eight years of economic stagnation.

The upheaval in Washington caused by Kennedy's murder allowed the real political master, Johnson, to emerge.

Here was a man who, unlike Kennedy, had raised himself up from poverty and obscurity to a position of unprecedented power in the Senate, and knew how to pull every lever, every manoeuvre. He had been a dominant Senate leader.

Caro writes: ''To watch Lyndon Johnson deal with Congress through the transition - to watch him break the unbreakable conservative coalition - is to see a President fighting with passion and determination but with something more … a gift, and a very rare one. To watch Lyndon Johnson during the transition is to see political genius in action.''

The virtuosity of Caro's narrative is driven by the depth and breadth of his research.

The book concludes with Johnson's marshalling of all his power and knowledge and animal magnetism to convert the shock of a presidential assassination into the sweeping reform of the Civil Rights Act, stymied for decades by the embittered congressional rearguard of the old South.

Today, politics is dominated by bitter rearguard actions. The Republicans refuse to raise taxes. The Democrats refuse to cut spending. The Eurocrats are addicted to policies that have driven Western Europe into structural stagnation. Reading Robert Caro reveals, in detail, how democracy itself can be the enemy of a nation's self-interest, and a single leader can make a difference.

Twitter: @Paul_Sheehan_