I. Alleluia. Though this word of praise appears to be of general application, it is exploited particularly at points of great exultation and joy. The Lord is praised by His people who are freed from worldly calamity and refuse to endure the slavery of vices. This praise is seen to convey the shape of the joy to come, when the Lord is beheld uninterruptedly by the faithful, and praised without end. As we read in another psalm: Blessed are they that dwell in thy house: they shall praise thee for ever and ever. 1 This psalm is also adorned with the sequence of the Hebrew alphabet, which is set down with all its letters at the head of the sentences or sections. It points out to us those just persons who by the gift of divine grace shine out with perfect virtues. Just as earlier alphabetic psalms which have certain letters missing indicate people who are not so endowed with every merit but are known to dwell in the holy gathering, 2 so the psalms with the full complement of letters seem to signify the merits of those outstandingly just. There is a further reason, as father Hilary says, for the insertion of this alphabet: "We know that children and the uninstructed are taught by letters to seek precepts of wisdom. In the same way psalms of this type are put before boys and learners so that their first lessons may be imparted by the letters acting so to say as teachers." 3 Though we have read that some people have learnt the divine Scriptures without knowing the letters, it is easier for our frail natures to learn wisdom by God's grace through letters than to achieve such a remarkable feat. So by this sacred sign we are advised to embark with speed and the utmost concentration on the pursuit of learning, for the very order of letters is set down so that we may ponder on and learn the rudiments.
The nation of the blessed have gathered from different parts of the world, and at the beginning of the psalm they say that they are confessing to the Lord in the gathering of the just, where praise is everlasting and celebration is without end. This first section contains six letters of the alphabet just mentioned. In the second section they say that His faithful are filled with His abundant gift, and together they