"Slave labor. That's what made this dinner. Slave labor." - Hermione Granger
The Seven of Wands is about aggression and defiance in a conflict. It signifies someone with strong convictions taking a stand against the norm.
It is a common viewpoint in wizard society that house-elves are inferior in status and naturally belong as servants in a household. In creating S.P.E.W., Hermione shows that she is not afraid to speak out against this popular attitude which she believes to be wrong. It takes a lot of bravery and confidence to oppose the majority opinion as she has done.
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