Treatise on the Mass (from the Stowe Missal), Part 02

Tocbál incailich iarnalándiurug quando canitur oblata isforaithmet gene Crist insin tre airde aindocbale [cor.: insin áindocbale tre airde] et [=ocus] firto · Quando canitur accipit Iesus panem · Tanaurnat insacart fathri duaithrigi dia pecthaib atnopuir deo [not in MS: ocus canaid in salmso Miserere mei deus] & slechthith inpopul & nitaet guth isson arnatarmasca insacardd ar issed athechte arnarascra amenme contra deum céne canas inliachtso isde ispericulosa oratio á nomen · Na · iii · chemmen ciṅges infergraith foracúlu & tociṅg afrithisi ised atrede inimruimdethar cachduine id est himbrethir hicocell hiṅgnim & ised ·iii· tresanaith nuigther iterum & trisatoscigther dochorp Crist :~

Tocbal in cailich iarn a landiurug, quando canitur Oblata, is foraithmet gene Crist insin [ocus] tre airde a indocbale (/ a indocbale tre airde) ocus firto.
Quando canitur: Accepit Iesus panem, tanaurnat in sacart fat(h)ri du aithrigi dia pecthaib; atnopuir Deo; ocus slecthith in popul: ocus ni taet guth isson, ar na tar masca in sacardd; ar issed a thechta ar na rascra a menme contra Deum, cene canas in liachtso. Is de is Periculosa Oratio a nomen.
Na tri chemmen cinges in fergraith for a culu, ocus tocing afrithisi, ised a trede in imruimdethar cach duine, idon, himbrethir, hi cocell, hingnim; ocus ised trede tressanaithnuigther iterum, ocus trisatoseigther do Chorp Crist.

The elevation of the chalice, after the full uncovering thereof, quando canitur Oblata (when Oblata is chanted), that is a memorial of the birth of Christ and of His exaltation through signs and miracles.
Quando canitur: Accepit Iesus panem (When is chanted: 'Jesus took bread'), the priest bows himself down thrice to repent of his sins. He offers them [i.e. the bread and chalice] to God, and the people prostrates: and there comes not a sound then, that it disturb not the priest, for it is his duty that his mind separate not contra Deum ('against', i.e. from, God) whist he chants this Lection. It is from this that Periculosa Oratio (the Most Dangerous Prayer) is its nomen (name).
The three steps which the ordained man stepps backwards and which he steps in return, that is the triad wherein sins any person, to wit, in word, in thought, in deed; and that is the triad through which he is renewed iterum (again) and by which he is moved to the Body of Christ.

Treatise on the Mass (from the Stowe Missal), Part 01

According to Wikipedia:

The Stowe Missal is a missal written in Latin and Gaelic which was transcribed at Lorrha Monastery in the ninth century. Also known as the Lorrha Missal, it is known as the 'Stowe' Missal due to its acquisition by one of the Dukes of Buckingham for the Stowe manuscripts collection. Stowe House was sold in 1849 to the Earl of Ashburnham. In 1883 the missal was purchased by the British Government and deposited in the Royal Irish Academy.

The form of the liturgy and the services of baptism and unction reflect a Celtic usage dating from before 650 AD. Whether this is the usage brought by St. Patrick in the early fifth century, or a later revision is not certain. Used during an era in which Christianity was neither universal nor fully understood, it asserts in detail the redemptive nature of Jesus Christ's birth, death and resurrection. The writer(s) assumes that those participating in the Eucharist must have every detail repeated clearly.

Here we are going to look upon a tract on the Mass (folios 65-67) written in Old Irish. I would first provide the original Gaelic and Latin text (as it appears in the Missal), a more 'tidied up' version (with proper spacings and punctuations), and an English translation.