IT is a truth not universally acknowledged that all life’s lessons can be found in fiction.

There remains an obstinate camp of readers who eschew fiction because “it’s all made up” yet surely there can be no more authentic depictions of mankind in the throes of violence, poverty, despair and, yes, hope and joy than in the works of Dickens, Dostoevsky or Tolstoy.

There is also no need to peer into the past for this education. Last year brought works by Kevin Barry and Bernardine Evaristo, in particular, that articulated truths that were both uncomfortable and inspiring.

Non-fiction, though, has its considerable strengths, and the reality of life lived has been a strong spine in this reader’s life. It falls into two categories, of course: biography and autobiography. Today’s sermon is on the former.

Autobiography seeks to explain. Those writing their lives seek love, pity or even forgiveness. It is a powerful cocktail that has produced great works. But as we stand at the doorway of a new decade it is perhaps more edifying to look at great biographies. These seek to ask questions, be less forgiving, and examine their subjects in a way that can be ruthless but ultimately of benefit to us all.

A detached biographer can extract extraordinary worth from the life of another. Take for example Robert A Caro, whose specialist subject is the accrual and exercise of power. He put this skill most famously to work in his magnificent four-volume history of Lyndon B Johnson. Yet in the accompanying panel to this article, I single out his The Power Broker, a life of Robert Moses who shaped the geography of New York to fit his will. This is power in action and at its most ruthless as houses were levelled, farms cut by swathes of roads and people re-located to fit the scheme of one man.

Similarly, Joachim Fest’s biography of Hitler is no one-dimensional rant against evil. Fest, whose memoir (Not I) shows him and his family as early and constant opponents of Hitler, places the dictator in a political, economic and social context. He shows how genuine horror can rise but also how Hitler used intelligence, an eerie charisma and a grasp of what people sought to become an unassailable leader. The biography is all the more frightening because of this readiness to explain rather than to indulge an incontinent desire to rail incessantly.

Biographies can also be remembered for the details – sometimes pathetic – that are keys to a life. Charles Moore wrote his life of Thatcher in three volumes, stretching over 2000 pages. The style is breathtakingly fluid, the research assiduous and exhaustive. He covers all the controversies, the rivalries, the rise and fall. It leaves, though, a piquant aftertaste. Moore, a journalist familiar to the tables of power, seems, like his subject, to have limited understanding of the world beyond Westminster, certainly in regards to the effects of Thatcherism. He states that Thatcher introduced “industrial peace”. One cannot resist the temptation to quote Tacitus: “Where they make a desert, they call it peace.”

More pertinently, however, Moore reveals how Thatcher was never blessed with an array of friends and how in her last, lingering illness (dementia) she was rarely visited by her children. There are truths that mark a life and the reluctance of children to visit their widowed mother must be one of the most brutal.

The detail in Peter Guralnick’s two-volume life of Elvis Presley is revealing, too. Guralnick describes a performer who changed the medium of music by irresistible presence and a burning self-belief that was reduced to a flicker when the music stopped. Indeed, it is this contrast between Elvis the performer and Elvis the individual that carries the biography into the highest reaches of the genre. And the detail? There is a moment when the reader witnesses a young Elvis devouring squirrel stew and suddenly the excess of later years becomes not only comprehensible but predictable. When one has paddled in poverty, it is easily to drown in riches.

This holds true of Francis Albert Sinatra, too, but James Kaplan’s two-part biography, offers other lessons. He persuasively advocates Sinatra as a genius, a man who could not read music but could mould it and make it matter to both the aficionado and the masses. But he also shows how Sinatra found happiness elusive and made others pay for his disaffection. He is a bully, a depressive, a user and abuser of women, yet he demands and receives extraordinary loyalty and enduring affection.

Kaplan, with a hip but never forced style, lays his subject open with the precision of a surgeon. Yet it is the reader who must make the diagnosis of the ills and appreciate the health of an extraordinary subject. It takes a writer of profound gifts to achieve this laying of indictments with a withholding of final judgment and not be criticised for prevarication. Kaplan succeeds brilliantly.

The juxtaposition of genius and genuine personal frailty is a motif of most biography. It exists in the magisterial three-part biography of Picasso by John Richardson, where the Spaniard is shown to have altered the way art sees people and things while treating human beings with a casual ruthlessness. It occurs, too, in When Pride Still Mattered by Dave Marannis, where the obsession of Vince Lombardi to create the perfect American football team leaves the Green Bay Packers as a legendary dynasty and Lombardi as the name of the Superbowl trophy, but condemns him to constant illness and his wife to solitary despair.

There are, however, many lessons in lives such as Sinatra, Picasso, Thatcher and Lombardi. There is powerful testimony to the efficiency of self-will, certainly in artistic and professional matters, but also the universal truth that life is a matter of balance and, regularly, choice. One can be defined by fate but destroyed by personal drives.

This simple realisation is the nub of the best biographies but there are those who offer a way forward. As 2020 blows in with its attendant crises, challenges and, hopefully, opportunities, reading can offer not only education but inspiration. It comes in its most distilled form in Sarah Bakewell’s How to Live Like Montaigne. The work and life of the 16th century French philosopher are examined and Bakewell produces something both sublime and practical.

Perhaps the ultimate lesson is that our lives are ours. But others have walked this way and can point to the pitfalls and the views of grandeur. It is our fate to learn by mistakes. It is our occasional consolation that we can learn by those of others.