On the evening of Tristram's conception (the first Sunday in March 1718), Mrs. Shandy asks a trivial question in the middle of that important event. The irritation it causes in his father has a negative influence on the "animal spirits" that control the makeup of the Tristram-to-be. The foundation has been laid for a "thousand weaknesses both of body and mind" in Tristram.
It was Uncle Toby who told Tristram the story of his conception; he told him also that when Tristram was young, Walter Shandy had observed many things about him that verified his opinion that the trouble had started on that fateful night. Mrs. Shandy, however, never knew or understood the slightest bit of this theory.
Tristram threatens that in telling his story he will not follow any of the rules laid down by the critics, but he realizes that curious readers want to know all the details from beginning to end. He explains that from information he has gleaned from his father's old memorandums, he is able to pinpoint the exact night of his conception. His father was "one of the most regular men in every thing he did"; for example, he wound up the family clock on the first Sunday night of every month and took care of "some other little family concernments" at the same time — once a month. The one thing and the other were always linked in his mother's mind, hence the question that she asked. He tells the day of his birth (November 5, 1718), and he says that his life has consisted of "pitiful misadventures and cross accidents," just as his father expected.
