The protagonist, Phil, is driven by his dream of becoming an artist. He has fierce ambition and prefers to focus on his dreams rather than the life he is in now.
This is shown by his decision to arrive at work late to accommodate his application to Art School and his nonchalant attitude to work and authority. He concentrates his efforts on where he want to be, even when it jeopardises his current position.
By the end of the play, Phil is further than ever from achieving his dream - jobless and rejected from Art School. Despite his bleak circumstances, Phil remains positive, cartwheeling and noting that:
Giotto was a Slab Boy!
He looks to Giotto as someone who rose from a humble position to achieve artistic greatness. This example of success helps Phil hold onto his dream that his ability and drive mean he can achieve anything.
Hector and Spanky do not share Phil's talent or ambition. Their dream of escaping the slab room is through the conventional route of promotion to the design room. The grim reality of this is laid out with Phil’s story of Joe McBride, the oldest Slab Boy in history:
in the slab room man and beast for nigh on sixty year.
By the end of the play, Hector is the only one to have secured his dream of a desk - a victory for the quietly focused, least disruptive victim of the group.
Spanky remains trapped in the slab room. He is more grounded than Phil and quickly settles into his fate:
Why don't you can it Phil? Me and the boy want to get cleared up.
Phil's dreams have a positive focus but many of the characters dream of escape from something rather than aiming for achievement.
Sadie shares her hopes of escape from her unhappy marriage. Her wearisome experiences in life have left her bitter and angry towards men. She diligently continues with her low paying, thankless job, but she is not filled with cynicism or self-pity:
I'm biding my time sweetheart. Soon as I've got a good wee bankbook I'm showing that swine the door.
Sadie's hopeful belief that she can save enough money to leave her husband and be liberated shows the importance of a dream in helping people cope with their gloomy circumstances.
While Phil is a character who pursues his dreams, Jack Hogg represents reality with his grounded outlook on life. He seems to recognise the value of Hector's limited and realistic goals. He accuses the Slab Boys of quashing Hector’s dreams claiming:
He used to come out to my desk… you soon put a stop to that… called him for everything… made his life a misery… Hector could’ve been a pretty good designer by now.
He is unimpressed with Phil’s daydreaming and has worked hard to achieve what he has:
There’s a real world out there. Some of us have to live in it.
The constant struggle between dreams and reality is evident throughout the play and Byrne leaves it to the audience to decide whether Phil’s hopeful optimism or Jack’s staunch pragmatism wins out.