Do I say that they ought at all hazards to set aside those differences, and in the name of their common faith and common danger undergo fusion,--to use an expression of the day,--and form hereafter but one and the same church? {22} I do not dream of it. The re-establishment of unity in the bosom of Christianity by the re-union of all Christian churches, has been the desire and the endeavour of the greatest minds, both Catholic and Protestant. Bossuet and Leibnitz have attempted it. Even now the idea is present to many noble spirits, and pious bishops have so expressed it to me, with a confidence by which I feel profoundly honoured. I respect the sympathetic wish, but I do not believe that it can be realised. Between temporal order and human interests, fusion, difficult as it may be, is always possible; for interests may be made to agree through the force and in the name of necessity. In spiritual order and between religious beliefs, no such agreement is possible, for necessity can never become truth. Faith does not admit of fusion; she insists on unity. But where the unity of the church does not exist, when the fusion of different churches is impossible, and when religious liberty is established, there is room for practical good sense and Christian charity. Good sense tells Christians that they are all in front of the same enemy, much more dangerous to them than they can be to each other; for should he triumph, the blow will fall on each. Amongst the upper classes, the war against religion manifests itself only under the forms of reserved scepticism or rationalism; timid, often serious and polite, rather seeking to screen than display itself. But at the bottom of society, and amidst the masses, it is passionate impiety which is at work, and for the sake of victory becomes subservient to the most gross and furious interests. The Christian faith, in its essential and vital character, that is, faith and submission to supernatural Christian order, is alone capable of sustaining the contest. {23} Let Christians, whether Catholic or Protestant, be convinced of it, the loss of credit and authority on either side would redound to the advantage not of Protestantism or Catholicism, but of impiety. It is then for all Christians, whatever their differences in their Christian sphere, an obvious interest and imperative duty to accept and maintain each other as natural allies against anti-christian impiety. It will require all their strength, all their united efforts, to triumph finally in this warfare, and save at once Christianity and society. What interest dictates to Christians, Christian charity commands. I use without hesitation plain words to express the ideas and sentiments which I feel, and even amidst the coldness of heart which is one of the most melancholy evils of my day, I feel no embarrassment in speaking to Christians of Christian charity.