This festival left on me the most melancholy impressions; I felt as though I had reached the meridian of my life, that I had in fact passed it, and that the string of the bow was over-stretched.  Mme. Wille told me afterwards that she had been overcome by similar feelings on that evening.  On the 3rd of April I sent the manuscript of the score of the first act of Tristan und Isolde to Leipzig to be engraved; I had already promised to give Frau Wesendonck the pencil-sketch for the instrumentation of the prelude, and I sent this to her accompanied by a note in which I explained to her seriously and calmly the feelings that animated me at the time.  My wife had for some time been anxious as to her relations with our neighbour; she complained with increasing bitterness that she was not treated by her with the attention due to the wife of a man whom Frau Wesendonck was so pleased to welcome in her house, and that when we did meet, it was rather by reason of that lady’s visits to me than to her.  So far she had not really expressed any jealousy.  As she happened to be in the garden that morning, she met the servant carrying the packet for Frau Wesendonck, took it from him and opened the letter.  As she was quite incapable of understanding the state of mind I had described in the letter, she readily gave a vulgar interpretation to my words, and accordingly felt herself justified in bursting into my room and attacking me with the most extraordinary reproaches about the terrible discovery she had made.  She afterwards admitted that nothing had vexed her so much as the extreme calmness and apparent indifference with which I treated her foolish conduct.  As a matter of fact I never said a word; I hardly moved, but simply allowed her to depart.  I could not help realising that this was henceforth to be the intolerable character of the conjugal relations I had resumed eight years before.  I told her peremptorily to keep quiet and not be guilty of any blunder either in judgment or in act, and tried to make her realise to what a serious state of affairs this foolish occurrence had brought us.  She really seemed to understand what I meant, and promised to keep quiet and not to give way to her absurd jealousy.  Unfortunately the poor creature was already suffering from a serious development of heart disease, which affected her temper; she could not throw off the peculiar depression and terrible restlessness which enlargement of the heart causes, and only a few days after she felt that she must relieve her feelings, and the only possible way in which she could think of doing so was by warning our neighbour, Frau Wesendonck, with an emphasis she thought was well meant, against the consequences of any imprudent intimacy with me.