What is "index librorum prohibitorum"

Index \In"dex\, n.; pl. E. Indexes, L. Indices(?). [L.: cf. F. index. See Indicate, Diction.]

1. That which points out; that which shows, indicates, manifests, or discloses; as, the increasing unemployment rate is an index of how much the economy has slowed.

   Tastes are the indexes of the different qualities of plants.
   --Arbuthnot.

2. That which guides, points out, informs, or directs; a pointer or a hand that directs to anything, as the hand of a watch, a movable finger or other form of pointer on a gauge, scale, or other graduated instrument. In (printing), a sign [[hand]] (called also fist) used to direct particular attention to a note or paragraph.

3. A table for facilitating reference to topics, names, and the like, in a book, usually giving the page on which a particular word or topic may be found; -- usually alphabetical in arrangement, and printed at the end of the volume. Typically found only in non-fiction books.

4. A prologue indicating what follows. [Obs.]
   --Shak.

5. (Anat.) The second finger, that next to the pollex (thumb), in the manus, or hand; the forefinger; index finger.

6. (Math.) The figure or letter which shows the power or root of a quantity; the exponent. [In this sense the plural is always indices.]

7. The ratio, or formula expressing the ratio, of one dimension of a thing to another dimension; as, the vertical index of the cranium.

8. A number providing a measure of some quantity derived by a formula, usually a form of averaging, from multiple quantities; -- used mostly in economics; as, the index of leading indicators; the index of industrial production; the consumer price index. See, for example, the consumer price index.

9. (computers) A file containing a table with the addresses of data items, arranged for rapid and convenient search for the addresses.

10. (computers) A number which serves as a label for a data item and also represents the address of a data item within a table or array.

11. (R. C. Ch.), The Index prohibitorius, a catalogue of books which are forbidden by the church to be read; also called Index of forbidden books and Index Librorum Prohibitorum.

    Index error, the error in the reading of a mathematical instrument arising from the zero of the index not being in complete adjustment with that of the limb, or with its theoretically perfect position in the instrument; a correction to be applied to the instrument readings equal to the error of the zero adjustment.

    Index expurgatorius. [L.] See Index prohibitorius (below).

    Index finger. See Index, 5.

    Index glass, the mirror on the index of a quadrant, sextant, etc.

    Index hand, the pointer or hand of a clock, watch, or other registering machine; a hand that points to something.

    Index of a logarithm (Math.), the integral part of the logarithm, and always one less than the number of integral figures in the given number. It is also called the characteristic.

    Index of refraction, or Refractive index (Opt.), the number which expresses the ratio of the sine of the angle of incidence to the sine of the angle of refraction. Thus the index of refraction for sulphur is 2, because, when light passes out of air into sulphur, the sine of the angle of incidence is double the sine of the angle of refraction.

    Index plate, a graduated circular plate, or one with circular rows of holes differently spaced; used in machines for graduating circles, cutting gear teeth, etc.

    Index prohibitorius [L.], or Prohibitory index (R. C. Ch.), a catalogue of books which are forbidden by the church to be read; the index expurgatorius [L.], or expurgatory index, is a catalogue of books from which passages marked as against faith or morals must be removed before Catholics can read them. These catalogues are published with additions, from time to time, by the Congregation of the Index, composed of cardinals, theologians, etc., under the sanction of the pope.
    --Hook.

    Index rerum [L.], a tabulated and alphabetized notebook, for systematic preservation of items, quotations, etc.

The Index Librorum Prohibitorum was a list of publications deemed heretical, anti-clerical or lascivious, and therefore banned by the Catholic Church.

The 9th century witnessed the creation of what is considered to be the first index, called the Decretem Glasianum, but it was never officially authorized. Much later, a first version (the Pauline Index) was promulgated by Pope Paul IV in 1559, which Paul F. Grendler believed marked "the turning-point for the freedom of enquiry in the Catholic world", and which lasted less than a year, being then replaced by what was called the Tridentine Index (because it was authorized at the Council of Trent), which relaxed aspects of the Pauline Index that had been criticized and had prevented its acceptance.

The 20th and final edition appeared in 1948, and the Index was formally abolished on 14 June 1966 by Pope Paul VI.

The aim of the list was to protect the faith and morals of the faithful by preventing the reading of heretical and immoral books. Books thought to contain such errors included works by astronomers such as Johannes Kepler's Epitome astronomiae Copernicanae, which was on the Index from 1621 to 1835, and by philosophers, like Immanuel Kant's Critique of Pure Reason. The various editions of the Index also contained the rules of the Church relating to the reading, selling and pre-emptive censorship of books—editions and translations of the Bible that had not been approved by the Church could be banned.

Catholic canon law still recommends that works concerning sacred Scripture, theology, canon law, church history, and any writings which specially concern religion or morals, be submitted to the judgment of the local ordinary. The local ordinary consults someone whom he considers competent to give a judgment and, if that person gives the nihil obstat ("nothing forbids") the local ordinary grants the imprimatur ("let it be printed"). Members of religious institutes require the imprimi potest (it can be printed) of their major superior to publish books on matters of religion or morals.

Some of the scientific theories in works that were on early editions of the Index have long been routinely taught at Catholic universities worldwide; for example the general prohibition of books advocating heliocentrism was only removed from the Index in 1758, but already in 1742 two Franciscan mathematicians had published an edition of Isaac Newton's Principia Mathematica (1687) with commentaries and a preface stating that the work assumed heliocentrism and could not be explained without it. The burning at the stake of Giordano Bruno, whose entire works were placed on the Index in 1603, was because of teaching the heresy of pantheism, not for heliocentrism or other scientific views. Antonio Rosmini-Serbati, one of whose works was on the Index, was beatified in 2007. The developments since the abolition of the Index signify "the loss of relevance of the Index in the 21st century."

A complete list of the authors and writings present in the successive editions of the Index is given in J. Martínez de Bujanda, Index Librorum Prohibitorum, 1600–1966. A list of the books that were on the Index can be found on the World Wide Web.