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The theme of opportunism can most clearly be seen in the way that rather unscrupulous individuals such as Thomas Putnam used the presence of his daughter in the group of girls to accuse people of witchery that he either had a personal grudge against or wanted removed so that he could gain their land. This is of course most strongly indicated in Act II when Giles Corey accuses Putnam openly of this, pointing to the deposition that he gives to Danforth:
If Jacobs hangs for a witch he forfeit up his property--that's law! And there is none but Putnam with the coin to buy so great a piece. This man is killing his neighbours for their land!
Thus we can see how Thomas Putnam saw the witch hunt as an opportunity for himself to gain greater riches and land, betraying innocent members of his own community to enrich his own position.