Commentary by Pir-o-Murshid Inayat Khan:
The loveless heart may have all the religion and all the knowledge, yet it is dead. As the Bible says, "God is love." God is in the heart of each person, and the heart of each person is the highest heaven. When that heart is closed by the absence of love, then God is closed. When this heart is open, God is open, and one is alive from that time.
~~~ "Gathekas #22, Aims and Ideals", by Hazrat Inayat Khan (unpublished)
When the heart is not empty, in other words, when there is no scope in the heart, there is no place for love. Rumi, the great poet of Persia, explains this idea more clearly. He says the pains and sorrows the soul experiences through life are like holes made in a reed flute, and it is by making these holes that a player makes the flute out of a reed. This means that the heart of man is first a reed and the sufferings and pains it goes through make it a flute which can then be used by God as the instrument for the music that He constantly wishes to produce. But as every reed is not a flute, so every heart is not His instrument. As the reed can be made into a flute, so the human heart can be turned into an instrument, and can be offered to the God of love. It is the human heart which becomes the harp of the angels. It is the human heart which is known as the lute of Orpheus. It was on the model of the heart of man that the first instrument of music was made, and no earthly instrument can produce that music which the heart produces, raising the mortal soul to immortality. ... It is the knowledge of the head and the love of the heart that together fully express the divine message. ... It is by keen observation that man acquires knowledge. Knowledge without love is lifeless.
In love abides all knowledge. It is mankind's love and interest in things that in time reveals their secret, and then man knows how to develop, control, and utilize them. No one can know anybody, however much he may profess to know, except the lover, because in the absence of love the inner eyes are blind. Only the outer eyes are open, which are merely the spectacles of the inner eyes. If the sight is not keen, of what use are the spectacles? It is for this reason that we admire all those whom we love, and are blind to the good qualities of those whom we do not love. It is not always that these deserve our neglect, but our eyes, without love, cannot see their goodness. Those whom we love may have bad points too, but as love sees beauty, so we see that alone in them. Intelligence itself in its next step towards manifestation is love. When the light of love has been lit, the heart becomes transparent, so that the intelligence of the soul can see through it. But until the heart is kindled by the flame of love, the intelligence, which is constantly yearning to experience life on the surface, is groping in the dark.
~~~ Knowledge without love is lifeless.