Hermann gazed at her in silence: his heart, too, was a prey to violent emotion, but neither the tears of the poor girl, nor the wonderful charm of her beauty, enhanced by her grief, could produce any impression upon his hardened soul. He felt no pricking of conscience at the thought of the dead old woman. One thing only grieved him: the irreparable loss of the secret from which he had expected to obtain great wealth.
Finally, after learning the card secret, Hermann greedily cheats others out of vast sums at the gaming table.
So he unrationally, so he can uncover the secret, for example, when he thinks of becoming the countess's lover. He then goes for Liza when this is unsuccesful.