I have also heard it said that understanding is the basis of all love, and I think this idea plays around the same concept. All of the great religious leaders preach practicing compassion, because in order for you to feel compassion towards someone, you must be able to understand what they are going through and to be able to imagine what they are feeling. When you can do this, you identify with them, you begin to feel their struggles as your own, and then you connect with them on an emotional level and feel their struggle as something more personal, and that is when you develop love for that person because you can not only sympathize but now also empathize with what they are going through. When you can connect this personally with another person, it is hard to feel feelings of hatred or fear, and dissolving these and replacing them to love leads to a lot more recovery and forward movement in the progression of humanity.