Mystici Corporis Christi §73

⁷³ But if the bonds of faith and hope, which bind us to our Redeemer in His Mystical Body are weighty and important, those of charity are certainly no less so. If even in the natural order the love of friendship is something supremely noble, what shall we say of that supernatural love, which God infuses in our hearts? "God is charity and he that abideth in charity abideth in God and God in him." The effect of this charity - such would seem to be God's law - is to compel Him to enter into our loving hearts to return love for love, as He said: "If anyone love me..., my Father will love him and we will come to him and will make our abode with him." Charity then, more than any other virtue binds us closely to Christ. How many children of the Church, on fire with this heavenly flame, have rejoiced to suffer insults for Him, and to face and overcome the hardest trials, even at the cost of their lives and the shedding of their blood. For this reason our Divine Savior earnestly exhorts us in these words: "Abide in my love." And as charity, if it does not issue effectively in good works, is something altogether empty and unprofitable, He added immediately: "If you keep my commandments you shall abide in my love; as I have also kept my Father's commandments and do abide in His love."