The titles of Psalms give the names of other collections from which individual psalms were taken. Thus twelve psalms, Pss. 42, 44-49, 84, 85, 87, 88, are hymns or songs of the Korahites, and eleven, Pss. 50, 73-83, of Asaph, who were according to the Chronicler--a good authority on the worship of his time--families, or hereditary guilds, of temple musicians, and seem, in this capacity, to have had special hymn books containing psalms which they sang, and which may also have been composed by members of the guild. The fact that the Korahite and Asaphite psalms are not scattered through the present Psalter, but appear in groups, and only in the elohistic hymn book (Pss. 42-89), confirms this view. When they were incorporated in the collection, the source was indicated by prefixing the name of the guild book to the individual psalms. Another group of fifteen psalms (Pss. 120-134) bear in their titles, "The Song of the Ascents," a phrase which, by the irregularity of its form, shows that it was transferred mechanically from the title of the collection ("The Songs of the Ascents") to the individual poems. The ancient interpretation makes the "ascents" the fifteen steps, or ascending platforms, on which the levitical orchestra stood at the festival of the water-drawing on the evening after the first day of Tabernacles (hence the Authorized Version, Song of Degrees, i.e. Steps). We need not discuss the question; that these psalms constitute a liturgical unit selected for a specific ceremony is plain. A considerable number of psalms have loosely prefixed to them the words Hallelu Jah (Praise ye Jah), which in the Hebrew text are frequently found at the end, having been erroneously carried back from the beginning of a following psalm. When this displacement (which is later than the Greek translation) is corrected, the Hallelujah psalms are 105-107, 111-118, 135, 136, 146-150. Here also a liturgical collection is naturally inferred. Jewish tradition informs us about the use of the "Hallel" (Pss. 113-118) and the "Great Hallel" (Ps. 136) at the festivals, and the name Hallel is also sometimes given to Pss. 146-148. Both the Hallels and the Songs of Degrees, it will be observed, are in the last of the three parts of the Psalter (Pss. 90-150). Of greater interest is the large collection of psalms which bear individually the name of David. This name is found in the titles of all the psalms in Book I. (Pss. 1-41), except Pss. 1 and 2, 10 (properly a part of 9, as in the Greek Bible), and 33 (in the Greek Bible Davidic); further, in Book II., two groups, Pss. 51-65, 68-70, and thereafter, scattering, Pss. 86, 101, 103, 108-110, 122, 124, 131, 133, 138-145--73 psalms in all, or almost half the Psalter. Manuscripts of the Greek Bible add a varying number of others, and other versions do the same.