Digressions are the sunshine, the life, and the soul of reading, says Tristram: "Take them out of this book for instance, — you might as well take the book along with them." The author's problem is serious: if he digresses, the whole book stands still, "and if be goes on with his main work, — then there is an end of his digression." But he has constructed the book so that, like one wheel within another, the "digressive and progressive movements" go on together, and "it shall be kept a-going these forty years."
If people had windows in their breast, we could tell at a glance what someone was like. But they don't, and we are liable to make many mistakes about their character. To avoid these errors, Tristram says, "I will draw my uncle Toby's character from his HOBBY-HORSE." It was an unusual hobby-horse, but before telling what it is, Tristram must first explain how Toby came to acquire it.
After being wounded in his groin, Toby was confined to bed for four years; since there was so much brotherly love between them, Walter took him into his house in London. Talking about the circumstances of his wound gave him much relief, so Walter gladly listened to his stories of the siege in which he was hurt. Something came up, however, that threatened to retard his cure. What it is, Tristram will tell about in the next book; the reader can't possibly guess.
