Anthony Jordan has put his finger on a very important component of Eamon de Valera's personality in this book, and if he has not quite penetrated to the core of the issue here, he has certainly given his readers a lot to think about.
Jordan emphasises the specifically Catholic dimension in de Valera's thought and politics, and he has written the familiar life story having cast the religious issue as a kind of Ariadne's thread that stretches from the loveless cottages of Victorian Bruree to Aras an Uachtarain in the Seventies.
Jordan presents startling evidence about the depth of de Valera's Catholic piety, noting the former Taoiseach's claim to have seen apparitions of Jesus of Nazareth, and the fact that he used to take Catholic relics in his pockets to key diplomatic summits throughout his career.
(Dev brought a relic of St Therese into Downing Street with him during the fraught negotiations that preceded the Anglo-Irish Agreement of 1938, making himself the first person to carry Roman Catholic icons across the threshold of that famous house since the days Gladstone perused his Douay Bible before bedtime in the 1860s.)
Having assessed all the major aspects of Dev's career from his Treaty tantrum in 1921 to his somewhat hasty resignation amidst controversy about his financial control of the Irish Press in 1959, Jordan concludes that his behaviour was shaped by the Catholic habit of so-called "mental reservation".
Based on the Catholic rejection of unmediated individual grace and its reliance on the confession sacrament in particular, Jordan suggests in his tantalising conclusion that this encouraged extreme or erratic patterns of behaviour if only because Catholics knew they could always seek absolution ex post facto.
In other words, the most apt phrase available to us as we try to understand the orphan who found solace in quaternion mathematics and the tuiseal gineadach is not "Up the Republic", but rather Augustine's "make me good Lord, but not yet".
Jordan is sensitive to the problem of violence in de Valera's life and to the way his martial instincts in 1916 and again in 1922 conflicted with aspects of the Catholic moral canon.
De Valera's analytical and moral contortions as regards violence call to mind the themes in Hubert Butler's "Little K", his extraordinary essay on the profound contradictions inherent in modern Catholicism's attitude towards life and death.
Much like the legions of European Catholics who preached the supreme value of "life" to their women folk while surrendering meekly to Hitler in the Thirties, de Valera had a similarly conflicted attitude towards the taking of life until well into the Thirties.
Butler was convinced that in many respects modern Catholicism was itself an elaborate theory of violence, and to that extent one should not be surprised by the Catholic Church's fatal torpor when confronted with Hitler.
De Valera's aggressive instincts between the Civil War smash and the murder of O'Higgins make sense when seen in the context of the a la carte aspect of modern Catholic ethics as emphasised so stylishly by Butler in 1967.
Jordan's book gives a lucid summary of the scholarly debate about Dev's constitution, and he included the lawyer Gerard Hogan's influential argument about the basically liberal architecture in Bunreacht na h-Eireann.
Jordan's overall thesis leaves another fairly tantalising question hanging in the reader's mind here: are the celebrated portions of the Bunreacht products of Dev's Catholicism rather than his liberalism?
Could it not be argued that his recognition of the dignity of the Jewish congregations in Article 44 drew on his profound religious faith which held that it was safer to recognise multiple religions in a constitution so as to better isolate liberalism, atheism and communism?
(Contemporary conservative American judges think like this when interpreting the First Amendment as can be seen for example in the writings of Professor Michael W McConnell, or even more clearly in Edmund Burke's earlier polemics.)
Judicial review of legislation is usually mentioned as well when de Valera's liberal credentials are being burnished.
But this desire to remove certain issues from the popular vote is also perfectly compatible with Catholicism's deep hostility to majoritarian democracy until fairly late in the 20th century, a subject upon which the Canadian (Catholic) Prime Minister Pierre Elliott Trudeau spilled much ink in the Fifties.
Dev famously said in 1922 that "the majority has no right to do wrong".
He meant it as statement of Republican principle, but this phrase could just as well have been uttered by great Irish Catholic bishops like James Warren Doyle or Daniel Murray in their battle against the majority's inconvenient support for alcohol, faction fighting and the Irish language.
De Valera's constitution was also very keen to make it clear that people have rights that are immune from government control, and these parts of the document have also been cited as examples of his pluralism.
But as the British philosopher Michael Oakeshott pointed out when he first read Bunreacht na h-Eireann, this catalogue of rights was really just a Hibernian version of Catholic natural law doctrine, a brackish pool indeed when you look in detail at its perished definition of sex equality and intellectual freedom in particular.
All of these somewhat cosmic questions await another day and another pen no doubt.
But Anthony Jordan has pointed us in some fascinating new directions in the seemingly unending debate about de Valera's life and thought.
John-Paul McCarthy holds a doctorate in Irish history from Oxford.
Sunday Indo Living