There have been innumerable attempts to classify and set 1 forth in order the multitudinous drives or motives which lead men to act as they do in society. Among Christians it is natural and proper to divide all human motives into those which are selfish and those which are unselfish; and further to say that all motives of the ‘natural man’ are fundamentally selfish, and only those of man under grace can really be unselfish. One thinks here of such analyses as that of Eros and Agape made by Anders Nygren in his work of that title; or of Augustine's famous distinction between earthly society (the civitas terrena) animated by love of self to the point of contempt for God, and divine society (the civitas caelestis) animated by love for God to the point of contempt for self. The danger, of course, of such vast generalisations is that they will be misunderstood by the disciples of the great men who originally made use of them—and even that they may mislead those great men themselves. It is obvious, for example, that Augustine is not here making the kind of distinction which is visible to direct empirical inspection. The two principles of which he speaks are principles of order which, he says, can be described mystically as two cities.1 Without attempting to go into the details of the interpretation of this great doctrine, it may be possible to make one point by way of introduction to our theme, a point which applies both to the distinction between Eros and Agape and to that between the two cities.