Selfishness, greed, egoism, vanity, pride and hatred contract the heart and stand in the way of developing universal love. When the heart is contracted through selfishness, man loves his wife, children, a few friends and relatives only, in the beginning. As he evolves, he loves the people of his own district, then the people of his own province. Later on, he develops universal love. All the barriers are broken now.
Heart expands infinitely.
It is very easy to talk of universal love. But when you want to put it in actual practice, it becomes extremely difficult. Petty-mindedness of all sorts comes in the way. The grace of the Lord will descend on you quite easily. Universal love terminates in Advaitic unity or oneness or Upanishadic consciousness of seers and sages.