The seventeenth century was a golden age of Augustinian historiography (history-writing). The most important Augustinian historical publication of the century was the work of Thomas Herrera O.S.A., who during that century was unsurpassed as the most scholarly historian of the Order.

He was born on 11th December 1585, joined the Order in 1600 and taught theology at Alcala, Spain from 1611 to 1623. In 1635 he became Prior of the famed Augustinian convento at Salamanca, Spain, and in 1639 was elected Provincial of the Castile Province, and in 1652 assistant general of the ultramontane provinces of the Order. He resigned the latter office to become confessor of the Infante Don Juan D’Austria, and died on 15th February 1654 at the age of sixty-nine years.

His best work is Alphabetum Augustinianum (“Augustinian Alphabet”), which was published in Madrid in 1644. It remains until this day as the only comprehensive reference work of Augustinian history. He began compiling it in Rome in 1633, and completed it at Salamanca in 1643. He used the following categories: Saints, Ministers of the Church and State, Writers, Famous Men, Famous Women, Monasteries of men, Monasteries of women. He combined the alphabetical order with a chronological sequence, without being slavish to either; this makes the finding of his material on lesser-known Augustinians somewhat difficult to locate.

The great asset of his work was his thorough and accurate searching for information in the Order’s main archives in Rome. His 800 pages of handwritten notes from those archives still exist in the National Library in Madrid, and contain some notes from some original archival materials that were subsequently lost or destroyed. He succeeded in additional Roman research, even in part of the papal archives and other Vatican sources. While travelling between Italy and Spain he managed to visit a number of Augustinian houses, and just as meticulously researched among their documents also; although obviously pressed for time when travelling, he never compromised on the high standards of accuracy and thoroughness.

Herrera had the disposition of a true historian, and his conclusions were always supported by facts. Two other historians were influential upon him in this regard: one was his teacher, John Marquez O.S.A., and the other a Franciscan, Luke Wadding. Wadding had written Annales Minorum (“The Annals of the Friars Minor”), and Herrera had undertaken extensive research for a similar Annals of the Augustinians, which he never completed (but his notes are still extant at the Angelica Library in Rome). Not that Herrera and Wadding agreed about everything; for example they engaged in a controversy in writing about whether Francis of Assisi had been an Augustinian before he founded the Order of Friars Minor (Franciscans). Herrera was in the act of preparing a further tract on his pro-Augustinian stance when death took him away, and the controversy faded away.

A number of Augustinians who had been fellow students of Herrera also ventured into Augustinian historical writing, but none were as professional in their historiography as Herrera had been. 
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