He knew, indeed, that the hand which still held Agatha's would in a moment be fettered, for Zminis had ordered his slaves to bring fresh ropes and chains, since they had already found use for those they had first brought out.

It was to this circumstance alone that he owed it that he still was free.

And, above all things, he must warn Agatha against the deaconess, who would fain persuade her to go with her.
It struck his alert wit that Agatha would trust his sister rather than himself, whom the Egyptian had several times abused as a criminal; and seeing the old woman of Polybius's household making her way up to Melissa, out of breath, indeed, and with disordered hair, he felt light dawn on his soul, for this worthy woman was a fresh instrument to his hand.

She must know Agatha well, if the girl were indeed the daughter of Zeno.
He lost not an instant.

With swift decision, while Zminis and his men were disputing as to whither they should conduct the traitor as soon as the fetters were brought, he released the maiden's hand, placing it in Melissa's, and exclaiming: "This is my sister, the betrothed of Diodoros, Polybius's son--your neighbor, if you are the daughter of Zeno.