4 Among them there is special reason why it pleases us to speak at present of the Church of the Ruthenians; not only is it outstanding for the number of its members and its zeal in retaining the faith, but also this is the three hundred and fiftieth year since it was happily restored to communion with the Apostolic See. It is, indeed, especially incumbent on those directly involved to celebrate this happy event in a spirit of gratitude, but we think it opportune also to recall it to the memory of all Catholics, so that they may ceaselessly give thanks to God for this great blessing, and also may join with us in earnest prayer that He would mercifully ease and alleviate the present distress and apprehension of this beloved people, would protect its most holy region, direct its constancy and preserve its faith unharmed.
Source: Orientales Omnes Ecclesias (Vatican.va)