8 You see, Venerable Brethren, how necessary it is to strive in every possible way that the charity of Jesus Christ should once more rule supreme amongst men. That will ever be our own aim; that will be the keynote of Our Pontificate. And We exhort you to make that also the end of your endeavours. Let us never cease from reechoing in the ears of men and setting forth in our acts, that saying of St. John: "Let us love one another" (I John iii. 23). Noble, indeed, and praiseworthy are the manifold philanthropic institutions of our day: but it is when they contribute to stimulate true love of God and of our neighbours in the hearts of men, that they are found to confer a lasting advantage; if they do not do so, they are of no real value, for "he that loveth not, abideth in death." (I John iii. 14).
Source: Ad Beatissimi Apostolorum (Vatican.va)