What are series tractors?

Famous quotes containing the words series and/or tractors:

    The theory of truth is a series of truisms.
    —J.L. (John Langshaw)

    I do not like football, which I think of as a game in which two tractors approach each other from opposite directions and collide. Besides, I have contempt for a game in which players have to wear so much equipment. Men play basketball in their underwear, which seems just right to me.
    Anna Quindlen (b. 1952)