Ecclesia de Eucharistia §44

⁴⁴ Precisely because the Church's unity, which the Eucharist brings about through the Lord's sacrifice and by communion in his body and blood, absolutely requires full communion in the bonds of the profession of faith, the sacraments and ecclesiastical governance, it is not possible to celebrate together the same Eucharistic liturgy until those bonds are fully re-established. Any such concelebration would not be a valid means, and might well prove instead to be an obstacle , to the attainment of full communion , by weakening the sense of how far we remain from this goal and by introducing or exacerbating ambiguities with regard to one or another truth of the faith. The path towards full unity can only be undertaken in truth. In this area, the prohibitions of Church law leave no room for uncertainty, in fidelity to the moral norm laid down by the Second Vatican Council. I would like nonetheless to reaffirm what I said in my Encyclical Letter Ut Unum Sint after having acknowledged the impossibility of Eucharistic sharing: “And yet we do have a burning desire to join in celebrating the one Eucharist of the Lord, and this desire itself is already a common prayer of praise, a single supplication. Together we speak to the Father and increasingly we do so 'with one heart'”.