The effect produced by singing depends upon the depth of feeling of the singer. The voice of a sympathetic singer is quite different from that of one who is heartless. However artificially cultivated a voice may be, it will never produce feeling, grace and beauty unless the heart be cultivated also. Singing has a twofold source of interest: the grace of music, and the beauty of poetry. In proportion as the singer feels the words he sings, an effect is produced upon the listeners; his heart, so to speak, accompanies the song.