When the day of Iseult's livery to the Lords of Cornwall drew near, her mother gathered herbs and flowers and roots and steeped them in wine, and brewed a potion of might, and having done so, said apart to Brangien: "Child, it is yours to go with Iseult to King Mark's country, for you love her with a faithful love. Take then this pitcher and remember well my words. Hide it so that no eye shall see nor no lip go near it: but when the wedding night has come and that moment in which the wedded are left alone, pour this essenced wine into a cup and offer it to King Mark and to Iseult his queen. Oh! Take all care, my child, that they alone shall taste this brew. For this is its power: they who drink of it together love each other with their every single sense and with their every thought, forever, in life and in death."
And Brangien promised the Queen that she would do her bidding.
On the bark that bore her to Tintagel Iseult the Fair was weeping as she remembered her own land, and mourning swelled her heart, and she said, "Who am I that I should leave you to follow unknown men, my mother and my land? Accursed be the sea that bears me, for rather would I lie dead on the earth where I was born than live out there, beyond. … One day when the wind had fallen and the sails hung slack Tristan dropped anchor by an Island and the hundred knights of Cornwall and the sailors, weary of the sea, landed all. Iseult alone remained aboard and a little serving maid, when Tristan came near the Queen to calm her sorrow. The sun was hot above them and they were athirst and, as they called, the little maid looked about for drink for them and found that pitcher which the mother of Iseult had given into Brangien's keeping. And when she came on it, the child cried, "I have found you wine!" Now she had found not wine - but Passion and Joy most sharp, and Anguish without end, and Death.
The Queen drank deep of that draught and gave it to Tristan and he drank also long and emptied it all.
Brangien came in upon them; she saw them gazing at each other in silence as though ravished and apart; she saw before them the pitcher standing there; she snatched it up and cast it into the shuddering sea and cried aloud: "Cursed be the day I was born and cursed the day that first I trod this deck. Iseult, my friend, and Tristan, you, you have drunk death together."