The preface states: “THE Syllabus of Pius IX. has been the subject of so many misconceptions, that a plain and simple setting forth of its meaning cannot be useless. This is what I have tried to do in the following pages. A vindication or defence of the Syllabus was, of course, out of the question in so small a compass; but I think more than half the work of defence is done by a simple explanation. During the ten years just completed since its promulgation, much has occurred to shew the wisdom that dictated it. The translation I have given is the one authorized ,by His Eminence the Cardinal Archbishop of Dublin.”And this is more true today. Benedict XVI called the Second Ecuminical Council of the Vatican , often called Vatican II, a 'counter-syllabus'. What he means by this is that Vatican II reversed the comdemnations of Pope Pius IX in the Syllabus of Errors. Let us return to the book: “THE Syllabus of Pius IX. is a series or catalogue of propositions, taken mostly from works of writers in our own century, and condemned by the See of Rome during the Pontificate of his present Holiness. The Syllabus itself was published on the 8th of December, Feast of the Immaculate Conception, in the year J 864 ; but all the propositions contained in it had been branded with Papal censure in some previous Bull, Brief, or Apostolic Letter, either in the reign of Pius IX. himself, or in that of his immediate predecessor, Gregory XVI. This will be seen from the references at the foot of each condemned thesis in the subjoined translation of the Syllabus, which give the date and title of the official document in which the said proposition had been previously censured. By glancing down the headings of the several classes in which the condemned errors are arranged, the reader will see that while some of them involve abstract doctrines, by far the greater part deal with those principles of Christian morals, which are developed and applied as the individual comes into contact with society and with the State. The Syllabus was accompanied by an Encyclical, or circular letter of His Holiness, addressed to "all Patriarchs, Primates, Archbishops and Bishops in communion with the Apostolic See." The tenor of the Encyclical, wherein the Holy Father commands all the children of the Catholic Church to hold every doctrine condemned by the Holy See as unlawful to be upheld or defended, coupled with subsequent declarations, leave Catholics no room to doubt that, in passing censure on each and everyone of these propositions, the Pope claims intellectual obedience on the ground of his infallibility.”This book should prove useful who wishes to study the Syllabus of Errors and Vatican II.