‘They must be guided by that universal love which is the compendium and most general expression of the Christian ideal, and which therefore may serve as a common ground also for those who have not the blessing of sharing the same faith with us. A great deal of confusion in the matter of co-operation with non-Catholics might have been avoided if we had insisted more strongly on the obvious sense of the words of Pope Pius XII in which he called for a common front in the promotion of peace. A common faith is expressly excluded as a basis of co-operation, nor is anything said here about a general recognition of the Natural Law; the common ground is discovered in universal love, an activity of the will rather than an intellectual outlook. That is not to say that we may not take full advantage of a genuinely Christian view of life in individuals who honestly fail to identify authentic Christianity with the Catholic Church, or that we may not expect others to observe the Natural Law and inculcate its precepts; but the one thing that we can generally demand is good will, which, as we know, is the condition for the infusion of sanctifying grace and supernatural charity. We cannot perceive the workings of grace, but we have to assume that one who gives signs of good will is imbued with this supernatural and universal love of which the Pope speaks, no matter what his speculative ideals may be. Such a basis is wide enough to include those who do not profess Christianity at all; as there are so many of them in Europe to-day, ‘those who have not the blessing of sharing the same faith ‘can scarcely be meant to cover only the various groups of non-Catholic Christians.