He_ knew that.

"That wasn't the only note he had written. He made Beulah write one,
too, addressed to Mary, and asking her to come to the Old Place, and be
secret about it. Ah, now you understand? But--I swear I didn't know
what he was leading up to. No, I didn't. I thought it was--well,
all's fair in love, you know. And I had to do what he said, I had to!

"Poor little Beulah had to do what he said, too. I only feared him,
but she loved and feared him both. He owned her completely. He had
made her into a regular echo of himself. She didn't want to, she cried
about it, but she had to do what he said.

"Mary came, as he knew she would. Didn't she have the kindest heart in
the country? And there he was, with Beulah, with his eyes on her, and
his soft, sly words making her lie seem more true. I heard it all. I
was upstairs. He placed me there, in case Mary didn't believe; then I
was to come in and tell about seeing you and Beulah together in Boston,
and how she begged me to bring her home. But--for God's sake!--I
didn't do it. I didn't have to. Mary believed. How could she help
believing--the gossip, and poor little Beulah sobbing out her story.
Beulah said it was you who got the best of her. She didn't want to say
it, she faltered and choked on the lie, but _his_ eyes were on her, and
his voice urged her, and so she had to say it. The very way she
carried on made the lie seem true.

"Well, Mary did just what he expected her to do. She promised to help
Beulah; she told Beulah she would make you make amends. Then she
rushed out of the house and met you coming along the cliff road--coming
along all spruced up, and with the look about you of one going to meet
a lady. Just as _he_ planned.

"What more could Mary ask in the way of evidence than the sight of you
in that place at that time? Of course she was convinced, completely
convinced. And she behaved just as he knew she would behave--she
denounced you, and threw your ring in your face, and raced off home.
And you behaved just as he knew you would behave. He was a slick
devil! He knew your pride and temper; he counted on them. He knew you
would be too proud to chase Mary down and demand a full explanation;
that you would be too angry to sift the thing to the bottom. You
packed up and went off to New York that night to join your ship--and
that was just what he wanted you to do.

"Next morning you were gone, and--they picked up little Beula