Harvey Riley, The Mule: A Treatise on the Breeding…
“ I do not mean to say that they cannot be got along the road; but I regard it no driving worthy of the name when a driver cannot get his team to any place where he may desire to go in a reasonable time--and this he cannot do with unbroken mules. With green or unbroken mules, you must chase or herd them along without the whip, until you get them to know that you want them to pull in a wagon. When you have got them in a wagon, pull their heads round in the direction you want them to go ”
