What precedes the draught of the potion in the drama, is narrative, explanatory and prefatorial. Once Tristan and Isolde have shared the goblet, passion is unleashed. The goal is death.
The magic love-philtre is the excitant in this story of rapture and gloom. The Vorspiel therefore opens most fittingly with a motive which expresses the incipient effect of the potion upon Tristan and Isolde. It clearly can be divided into two parts, one descending, the other ascending chromatically. The potion overcomes the restraining influence of duty in two beings and leaves them at the mercy of their passions. The first part, with its descending chromatics, is pervaded by a certain trist mood, as if Tristan were still vaguely forewarned by his conscience of the impending tragedy. The second soars ecstatically upward. It is the woman yielding unquestioningly to the rapture of requited love. Therefore, while the phrase may be called the Motive of the Love-Potion, or, as Wolzogen calls it, of Yearning, it seems best to divide it into the Tristan and Isolde Motives (A and B).
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The two motives having been twice repeated, there is a fermate. Then the Isolde Motive alone is heard, so that the attention of the hearer is fixed upon it. For in this tragedy, as in that of Eden, it is the woman who takes the first decisive step. After another fermate, the last two notes of the Isolde Motive are twice repeated, dying away to pp. Then a variation of the Isolde Motive
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leads with an impassioned upward sweep into another version, full of sensuous yearning, and distinct enough to form a new Motive, the Motive of the Love Glance.
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