34. An example of the forbidden mixing of rite would be a Latin consecrating leavened bread and giving communion from it to Latins. It would be the same if Orientals who do not consecrate unleavened bread were to do so and to distribute it to their people for holy communion. Latin Ordinaries who have Italian Greeks subject to them should show a careful concern "that Latins receive communion from unleavened bread and Greeks from leavened bread where they have their own parish" (Our constitution Etsi Pastoralis, sect. 6, no. 14).

Another example of forbidden mixing of rites would be a priest celebrating Mass at one time according to the Latin rite and at another time according to the Greek rite. St. Pius V forbids this in his constitution 21, Providentia (Bull. novi, vol. 4, pt. 2, Rome). He revokes absolutely all faculties of so doing which had previously been granted to-some priests. Our constitution 57, sect. 7, no. 10, agrees with this constitution of Pius V. Even though priests in charge of colleges of Orientals in Rome who became Jesuits and transferred from the Greek to the Latin rite have received a dispensation to sometimes offer the sacrifice of the Mass in the Greek and Oriental rite, as already mentioned, this has been approved in order that their students may learn how to celebrate Mass in their own rite since they are bound to profess the Greek and Maronite rite and conduct divine services in accordance with it thoughout their lives. The particular circumstances of this obviously unique case show clearly enough that it cannot be used as an exemplary argument for gaining similar dispensations.

Cardinal Kollonitz advised Pope Clement XI that allowing Latin missionaries in Hungary to celebrate in the Greek rite whenever this appeared necessary, while remaining at liberty to return to the Latin rite, would be beneficial to the Church. The Pope rejected the Cardinal's advice because he felt that each one should remain in his own rite in accordance with the provisions of the Canons and that a priest should not be permitted to change the rite in which he celebrated Mass. This is clear from his Brief to the Cardinal on May 9, 1705 (Epistolar. et Brev. selectior, ejusdem Pontificis typis editor, p. 205).