Rich and Poor
The Salvation Army accepting donations from Undershaft and Bodger but not taking Bill's money is a metaphor about the class system. That the Salvation Army is willing to forgive the sins of the wealthy and receive their money, but not those of the poor: that the poor's money isn't enough for them, they desire their salvation rather than just their money. It is showing that the rich are able to buy their salvation without ever giving their hearts.
Greek Lesson
Adolphus accepting to inherit Undershaft's fortune is a metaphor that he believes there is no way to bring freedom to the common man. That those in power will stay in power whether elected to their post or by inheriting it. He has lost his belief that man can rise in class with his mind, that there is only the hope of equality through force.
Salvation Army
Barbara leaving the Salvation Army is a metaphor that Salvation comes not through an organization, nor a ruling class. Instead, it comes from a personal choice. Barbara, though she has lost her position with the Salvation Army still has her belief that she was made to save souls and is further convicted to do so through her father's factory.
Foundling
The Undershaft dynasty only being able to be passed down to a foundling is a metaphor for breaking class traditions and allowing fluidity within the class system in England. Shaw deals directly with the issues of class in this play and throws into question the actual recipient of the inheritance of war. Is it the ruling class? No, Shaw says that the common man will inherit the necessity to go to war and to continue to perpetrate death upon the earth as the upper classes continue to desire submission from them.
Carriage
Undershaft offers to drive two others with him to his factory, but his car is not painted. Lomax is grateful to not have to ride with him as he is fearful to lose face by being seen in an unpainted vehicle. It's embarrassing to him. This is a metaphor for the upper class' unwillingness to lower themselves in any regards that would give anyone a thought that they had lost their wealth and are poor.
