Graduale or gradale) is used of a service book or antiphonal of the Roman Catholic Church containing certain antiphons, called "graduals," sung at the service of the Mass after the reading or singing of the Epistle.
During the distribution antiphons are sung.
Gradually there were added to these psalter choir-books additions in the form of antiphons, responses, collects or short prayers, for the use of those not skilful at improvisation and metrical compositions.
This was mainly carried out by the adoption of a rule that all antiphons and responses should be in the exact words of Scripture, which, of course, cut out the whole class of appeals to created beings.
This is the very backbone of the Breviary, the groundwork of the Catholic prayer-book; out of it have grown the antiphons, responsories and versicles.