Symbol for inferiority
When Clive presents Joshua, it is mentioned how his skin is black even though the stage directions present him as being white. The fact that he has "black’’ skin is important because Joshua sees himself as being inferior just because of his skin. Thus, the black skin is used here as a symbol of inferiority while the white skin is used as a symbol for superiority.
I will do as father commands
One of the common motifs found in the play is the way in which every character sees Clive as being superior and worthy of being worshiped almost. No one dares to challenge him and he is presented as always having the last word. Clive is more a dictator than anything else and his word is law for the rest of the family. This attitude is a common motif which is maintained until the end of the play.
It is not too cold?
Another common motif which appears in the play is the idea that the weather can be dangerous for the characters in the play. The women especially are always obsessed whit the weather and question themselves if they are overdressed or underdressed. The weather can also be considered as symbol, used here to suggest the dangers the characters were exposing themselves in Africa.
Symbol for adulthood
During the Christmas celebrations, Clive decide to let his son Edward have a glass of champagne, like the rest of the adults present at the celebrations. The moment when Edward is given alcohol to drink is important because from that moment on he starts behaving with his sister and his mother just like his father wants to, namely by looking down on them and seeing them as being inferior. Thus, the act when Edward drunk the Champaign is used as a symbol for adulthood.
Killing us in our sleep
Another common motif found in the play is how the characters fear they will be killed by the Africans near them. Because of this, the characters carry their guns with them, always ready to protect themselves. This is a common motif in the play and remains one especially in the first Act.