1. A yearning or longing for something that cannot be expressed or quantified.
2. The sweetest thing in all my life has been the longing — to reach the Mountain, to find the place where all the beauty came from — my country, the place where I ought to have been born. Do you think it all meant nothing, all the longing? The longing for home? For indeed it now feels not like going, but like going back. — C.S. Lewis, Till We Have Faces
3. When I was a child I caught a fleeting glimpse out of the corner of my eye. I turned to look but it was gone. I cannot put my finger on it now. — Pink Floyd, Comfortably Numb