We find innumerable examples, in the lives of the saints, of the love of neighbor which Christ commands.  In his biography of St. Martin of Tours (d. 397), his friend Sulpicius Severus (d. 425) tells a story about the neighborly love that filled Martin's heart even while still an unbaptized Roman cavalry officer: 

"One time, in the middle of the winter (which was more severe than usual, so much so that the force of the cold killed many), when he himself had on nothing besides his arms and his simple military dress, he encountered a poor man without any clothes in the port city of Ambianensium [in Gaul].  He was begging the people who were passing by to take pity on him, but everyone continued past the wretched man.  Martin, filled with God, understood that this man was reserved for him, since  none of the passersby had shown any mercy.  But what should he do?  He had nothing but the military cloak which clothed him, for he had already given away the rest of his clothes in similar work.  He snatched out the sword with which he was girded, and cut his cloak down the middle.  He gave part to the poor man, and dressed himself again with what was left.  Meanwhile, he was laughed at by some of the people standing around because he seemed unsightly, with his cloak cut up in that way.  But others, of sounder mind, groaned deeply that they had done nothing similar.  And since they had more, they could have clothed the poor man without leaving themselves naked.  That night, when Martin had given himself over to sleep, he saw Christ dressed with the part of the cloak with which he had clothed the poor man.  He was told to look with great attention at The Lord and to recognize the part of his cloak which he had given.  Then he heard Jesus say in a loud voice to the multitude of angels around him, 'Martin, who is still a catechumen, has clothed me in his cloak.'  The Lord, truly mindful of the words he had said on earth -- 'As often as you did for the least of my brothers, you did for me' -- declared that he had been dressed in the poor man, and to confirm the testimony of so good a work, he deigned to show himself in the same dress which he had received as the poor man.  When the most blessed Martin had seen this, he did not puff himself out in human glory, but recognizing the goodness of The Lord in his work, he ran hastily to be baptized when he was twenty-two years old."