Lyric discussion by zoeface 

Cover art for Blue lyrics by Joni Mitchell

she also connects songs to be like tattoos, and I think that, like in a lot of her songs, her choices about music have both given her purpose and made her lonely. The business is tempting her into its traps like 'Acid, booze, and ass, needles, guns, and grass', but in proclaiming her love for Blue she is trying to stay in touch with her love of music and reality.

Blue, here is a shell for you Inside you'll hear a sigh A foggy lullaby There is your song from me

I think this is referring to making an imprint on the music scene and being properly understood, perhaps some self-doubt in 'a foggy lullabye'?