Euclid's parallel postulate may not have seemed so important when you studied geometry in high school, since it is used only once in order to derive the basic result 1 on alternate interior angles, which is then constantly used to derive further results.

Brother Rosell, in my right hearty wise I commend me unto you, and in like wise unto my sister your bedfellow, &c.

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Wisps of straw stuck in the workdog’s coat, mud was on her feet, she reeked of cow.