How we cite our quotes: (Chapter.Page)
Quote #7
'King Mark,' he said, 'whoever advised you to make this accusation did you a terrible wrong and certainly acted disloyally. You are easily influenced, but you must not believe false words.' (15.140)
Arthur is correct that Mark is easily influenced, but not to say that Mark has believed "false words." What his barons have told Mark is technically true. However, their words may be false in the sense that they are not uttered with Mark's best interests at heart, but out of jealousy and spite for Tristan.
Quote #8
'She has done everything that justice demands, and she put more into her oath than the villains required her to. She needs to make no defence concerning the king and his nephew beyond what all of us have already heard. She swore in her oath that no man ever came between her thighs, except the leper who carried her across the ford yesterday morning and King Mark, her husband. A curse on anyone who mistrusts her now!' (15.142)
The audience for Yseut's oath believes she has done more than was required by giving the details of her sexual history, since in fact all that she was asked to swear was that she never had Tristan as a lover. Yseut's oath here is "equivocal" because it is technically true, but misleading. It depends on everyone's misunderstanding of the identity of the leper who carried her across the ford, and on their assumption that he has been between her thighs only once.
Quote #9
Yseut of the White Hands had heard Tristan's instructions to his messenger, and out of jealousy she told him falsely that the sails were black. Believing that at the last his beloved Yseut had failed him, Tristan fell back on his bed and died. (19.165)
It's possible to read Tristan's death as a taste of his own medicine, in more ways than one. He has received his wound helping a friend carry on an adulterous affair. (What does this say about Tristan's attitude toward adultery in general?) But he dies because of a lie his wife tells. Given the lies and deception in which Tristan and Yseut have engaged, their deceit-driven death seems somehow appropriate.