We have chosen to dwell at length on the Jubilee because, not only does it serve as a useful illustration of CST, but at the same time it reveals the timelessness of Catholic principles. Having established this basis, we will begin to make extensive use of those documents which are much more recent. In addition to the use of scripture, the Church Fathers, and various official documents produced by the Church itself, we will make frequent use of the Angelic Doctor, St. Thomas Aquinas. We feel comfortable utilizing an individual such as Aquinas only because, in doing so, we are conforming to the attitude of the popes themselves. St. Pius X was not expressing a private opinion when he said:
“In the first place, with regard to studies, We will and ordain that scholastic philosophy be made the basis of the sacred sciences…And let it be clearly understood above all things that the scholastic philosophy We prescribe is that which the Angelic Doctor has bequeathed to us…Further, let Professors remember that they cannot set St. Thomas aside, especially in metaphysical questions, without grave detriment.”
We will also attempt to limit our study specifically to those sources which are readily available on the internet. Every source used here, from the Compendium of the Social Doctrine of the Church, to the Catechism, to the Summa Theologica of St. Thomas Aquinas, can be found online by anyone with an internet connection. My hope is that most readers will take advantage of this fact in order to verify and study in greater depth any sources they find meaningful or interesting.
The various encyclicals, the Compendium, the Catechism, and most of the other documents cited below are available at the Vatican website: http://www.vatican.va/archive/index.htm
The Summa Theologica of St. Thomas Aquinas, The Catholic Encyclopedia and many other significant writings are available from New Advent: www.newadvent.org
The remainder of Aquinas’ works can be obtained from the Dominican House of Studies: www.dhspriory/thomas
Finally, the reader should be aware that we will not limit ourselves only to those documents normally associated with CST—which is in fact a very specific and limited corpus. This is because the documents specifically associated with CST, in their approach and in their manner of speaking, often take for granted a certain degree of familiarity with doctrine. This is a degree of familiarity which, in our time, it is not possible to presume.
For example, all of the documents of CST presuppose an acceptance of Catholic moral philosophy, which, sadly, is often lacking. Even those members of the laity who are open to the teachings, and who believe themselves to be in complete conformity with the Magisterial position, may find that in fact they have never even heard of some of her principles. And so, when we arrive in our study at sections which presuppose Catholic moral philosophy, we will veer away from the corpus of CST in order to explore documents from other areas, such as St. John Paul II’s moral encyclical, Veritatis Splendor. This is not because Veritatis Splendor is the only document to speak on morality, but because it is the first document to synthesize the moral teachings of the Church for the benefit of all its members and to publish them in such succinct form. As the document itself states:
“This is the first time…that the Magisterium of the Church has set forth in detail the fundamental elements of this teaching, and presented the principles for the pastoral discernment necessary in practical and cultural situations which are complex and even crucial.”
Other “necessary digressions” of this sort may be expected to occur throughout the work.
 PDG, 45.
 VS, 115.