Take, 'Yer Blues," for example. Have you ever felt alone? Felt like the things in life that brought you enjoyment are no longer fulfilling? Have you ever felt like dying?
Sure it's just a song, but the songwriter is sharing some deep pain, and emotions. Lennon exposed himself emotionally in many of his songs. Often saying or expressing deep seeded fears, concerns, emotions and personal reflections.
Lennon has no answer for his loneliness, except for the line, "If I ain't dead already, girl you know the reason why." We look for escape from our problems in so many things; sex, drugs, fame money, but they are only temporary.
If you want real peace, look to the Lord. I do not know the state of John Lennon's soul. I know that he was a troubled man, that found peace. Rumors have him being saved during his five year sabbatical from the business , I would hope so.
Peace I leave with you, My peace I give to you; not as the world gives do I give to you. Let not your heart be trouble, neither let it be afraid."-John 14:27 (Ironic, huh?)