Very few are the parts of running water, found between its surface and its bottom, that run to one and the same aspect.

c - a b - d

The water a b runs along the line of the object under the contrary motion c d b, which, by means of the eddy, has dug out the bottom beneath itself; in which depth the said water a b runs and is thence swept away with the same velocity as the revolution of the aforesaid eddy.

Why do dogs willingly smell one another's rear? This animal hates the poor, because they eat wretched food, and loves the rich, because they have good viands, and above all of meat; and the dung of animals always retains something of the virtue of its origin, as the mesenteric veins show, distributed even into the last depths of the intestines to draw to themselves from those feces the virtue that remains there. Now dogs have so very subtle a sense of smell that with their nose they perceive the virtue remaining in such feces. And that this is true: if they find them along the roads, they smell them, and if they sense within them the virtue of meat or of other things, they take them, and if not, they leave them. And to return to the question, I say that if they recognize by such smell that the dog is well fed, they respect it, because they judge it to have a powerful and rich master; and if they do not sense such smell with virtue, they judge such a dog to be of little worth and to have a poor and wretched master, and therefore they bite such a dog as they would its master.