The plague of darkness serves two functions in terms of both maintaining and highlighting the difference between the Jews and their Egyptian taskmasters.
Yaakov sends Yosef on a mission from history to destiny
Three ideas about the emphasis the Torah places upon the manner in which Yaakov Avinu takes the gifts he sends to his brother.
The false expectations of others cause the beauty of Leah Imenu to be obscured by anxiety and grief.
In the midst of a famine in a place where the local population does not easily abide his presence, Yitzchak Avinu finds material success--and gives back a tithe.