Ticket 54: Unify Your Lyrical Imagery/Extended Metaphor

Draw all your metaphors and similes from a narrow pool of concepts

Julia - sea and sky
Piggies

also

Birches (Bill Morrissey)

Crosstown Traffic (Jimi Hendrix)
Expressway To Your Heart (Blues Brothers)
Faster (Than The Speed Of Light) (Matt Blick)
Hotel California (The Eagles)
I Can See Clearly Now – weather (Johnny Nash)
Oh, If I Had A Golden Thread (Pete Seeger)
People Get Ready – train (Curtis Mayfield)
Say Goodbye To The Fairground (The Pearlfishers)
Spanish Harlem – flowers (Ben E. King)
Send in the Clowns – (Stephen Sondheim)
The Last Chance Texaco – cars parts/oil companies (Rickie Lee Jones)

There Goes The Moon (Matt Blick)

See also

Ticket 24: Use Parallel Lyrics
Ticket 49: Employ Madrigalism
Ticket 64: Try Writing For Kids
Ticket 66: Write An 'Occasional' Song

See the full list of songwriting tips here - Tickets To Write

Thanks to Nancy Rost and Jonathan Nelson on the BSA forum for examples