Humanism, even humanism of the distinctly individualistic type I have been outlining, may, as I have already suggested, work in harmony with traditional religion. In that case there must be a careful determination of boundaries. Though humanism and religion both lie on the same ascending path from the naturalistic flux, one must insist that each has its separate domain. It is an error to hold that humanism can take the place of religion. Religion indeed may more readily dispense with humanism than humanism with religion. Humanism gains greatly by having a religious background in the sense I have indicated; whereas religion, for the man who has actually renounced the world, may very conceivably be all in all. On the other hand, the man who sets out to live religiously in the secular order without having recourse to the wisdom of the humanist is likely to fall into vicious confusions--notably, into a confusion between the things of God and the things of Cæsar. The Catholic Church has therefore been well inspired in rounding out its religious doctrine with the teaching of Aristotle and other masters of the law of measure. It can scarcely fail to recognise that the position of the positive and critical humanist is sound _as far as it goes_. It follows that the Catholic and the non-Catholic should be able to co-operate on the humanistic level. A like co-operation should be possible between the humanist and the members of other Christian communions who have not as yet succumbed entirely to humanitarianism.