Certain great days of the Church are so important in the truths they set forth, the Church hath thought good to order that all Holy Scriptures that can possibly be used in illustration thereof shall be read on those days. Thus in addition to the Proper Lessons there are also Proper Psalms, and the days for which they are appointed with the number of the Psalms to be read are to be found in the Table prefixed to the Psalter in the Prayer-book.