St. Augustine of Hippo (354-430) was one of the most prolific geniuses that humanity has ever known, and is admired not only for the number of his works, but also for the variety of subjects, which traverse the whole realm of thought. The form in which he casts his work exercises a very powerful attraction on the reader. The fifteen books De Trinitate, on which he worked for fifteen years, from 400 to 416, are the most elaborate and profound work of St. Augustine. The last books on the analogies which the mystery of the Trinity have with our soul are much discussed. The saintly author himself declares that they are only analogous and are far-fetched and very obscure.