This congregation, so called from the Index or catalog of forbidden books, was created by Pope Pius V in 1571. Pope Benedict XV suppressed it on March 25, 1917, its duties being left entirely to the Holy Office. The Congregation of the Index consisted of a number of cardinals, one of whom was its prefect. The Master of the Sacred Palace (a Dominican) was ex officio its assistant, and another Dominican its secretary. There was also a college of consultors whose office was to deliver written opinions on the books submitted to their judgment by the congregation. The congregation censured and condemned books which it considered dangerous to faith or morals. It could grant permission for the reading of a condemned book, or for the publication of corrected editions. The congregation was also charged with the work of seeking out pernicious publications, and, after mature examination, of condemning and proscrlbrng them.