“The greatest commandment in the law is to love God with one’s whole heart and one’s neighbor as oneself (cf. Matt 22:37-40). Christ made this commandment of love of neighbor His own and enriched it with a new meaning. For He wanted to equate Himself with His brethren as the object of this love when He said, ‘As long as you did it for one of these, the least of My brethren, you did it for Me’ (Matt 25:40). Assuming human nature, He bound the whole human race to Himself as a family through a certain supernatural solidarity and established charity as the mark of His disciples, saying, ‘By this will all men know that you are My disciples, if you have love for one another’ (John 13:35).” (Pope Paul VI, Apostolicam Actuositatem, 1965, Sec. II.8)