This is Teresa's "curse" that Nostromo later takes to heart, and to
avoid which he steals the cargo of silver. But if character is the true treasure,
then Teresa's curse comes true, for by stealing the silver Nostromo is bereft
of the purity of character he possessed before. Note that, the voice of class-conscious
material welfare having spoken, whatever choice Nostromo makes about the
lost silver is a "folly," and will betray him into poverty of one sort
or the other.