"Free from the prison of the body...": that's what carnis liber ergastulo means in the Vesper hymn for St Dominic's feast day – much to the embarrassment of the Dominicans I knew, who were so insistent that their holy founder preached against the dualist heresy of the Albigensians which regarded matter as evil!
An ergastulum was apparently a rather nasty roofed-in pit in which dangerous slaves, or those undergoing punishment, were kept enchained; they were common, alas, on the great Roman landed estates worked by slaves, until the Emperor Hadrian outlawed such prisons as overcruel. I suppose we are to see this miserable and naughty world as such a prison, or, rather, the body itself as such a pestilent prison in which doth languish the soul.
Ever since the Fall, the complex unity of body and soul has been in disarray, the soul grievously lacerated, the body no longer perfectly subject to the soul's sway; perhaps thus the body would be viewed as a house ruinous, from which the soul is set "free among the dead" (Ps 87), especially as the soul of a saint such as Dominic is necessarily perfected by grace and therefore raised to heaven.
Apart from what does appear a somewhat pessimistic thought, the Office of St Dominic, read this day, the 4th of August, in the traditional calendar, is quite beautiful. It is a rhyming or rhythmic office, in that the antiphons and long responsories are composed in rhyming verse.
At first Vespers, the great responsory O spem miram is sung (otherwise used monthly at Compline in choir, as a special devotion to St Dominic); at second Vespers, the magnificent O lumen Ecclesiæ (repeated every night at Compline in his honour) is the Magnificat anthem – it shares a common chant melody with the O quam suavis est of Corpus Christi, and the Sanctus of Mass VIII (de Angelis), though I think the music dates back to yet another original.
During the former Octave of this feast, daily at Lauds the Benedictus anthem was the following, which deserves rescue from oblivion:
Benedictus Redemptor omnium, qui saluti providens hominum, mundo dedit sanctum Dominicum.
(Blessed be the Redeemer of all, Who providing for the salvation of men, gave to the world holy Dominic.)
Much if not most of this Office deserves careful consideration and meditation; here is part of the hymn at Lauds:
Spargens per orbis cardinem,
Pestem fugat hæreticam,
Novum producens Ordinem.
(Scattering the evangelical doctrine throughout the ends* of the world, he drove away the heretical pest, producing a new Order.)
[*More literally, the "cardinal points".]
I particularly like the passage chosen from Ecclesiasticus chapter 50 for the little chapter at both Vespers, Lauds and Terce (after which High Mass would be sung):
Quasi stella matutina in medio nebulæ, et quasi luna plena in diebus suis, et quasi sol refulgens, sic iste effulsit in templo Dei.
As the morning star in the midst of a cloud, and as the full moon in its days, and as the shining sun, so did he shine forth in the temple of God.