"It is better either to buy, from a shepherd, dogs which are accustomed to follow sheep or dogs which are without any training at all. While a dog does readily whatever he has been trained to do, his affection is apt to be stronger for the shepherds than for the flock.[144] "Once P. Aufidius Pontianus of Amiternum bought certain flocks of sheep in further Umbria, the dogs which herded them being included in the bargain, but not the shepherds, who were, however, to make the delivery at the Saltus of Metapontum and the market of Heraclea: when these shepherds had returned home, their dogs, longing for their masters, a few days later of their own will came back to the shepherds in Umbria, having made several days journey without other food than what the fields afforded. Nor had any one of those shepherds done what Saserna advises in his books on agriculture, 'Whoever wishes to be followed by a dog should throw him a cooked frog.'[145] "It is of importance that all your dogs should be of the same breed, for when they are related they are of the greatest aid to one another. "Now as to Scrofa's fourth consideration, that concerning the manner of buying: this is accomplished by delivery by the former owner to the purchaser. "The same stipulations as to health and against liability for tort are made as in the case of cattle, leaving out whatever is inapplicable to dogs. Some make a price on dogs at so much per head, others stipulate that the puppies shall go with the mother, others that two puppies shall count as one dog--as two lambs usually count as a sheep. Usually it is provided that all the dogs which have been accustomed to be together should be included in the bargain. "The food appropriate for dogs is more like that of man than of sheep, for they are fed on scraps and bones rather than on grass and leaves. Care must be taken that they are fed regularly, for, if food is not provided, hunger will lead them in search of it away from the flock, unless, indeed, they shall find it in one another, thereby contradicting the old proverb,[146] or perchance they may realize the fable of Actaeon and turn their teeth against their master himself. You would do well to feed them on barley bread soaked in milk, because when they have become accustomed to that diet they will not readily desert the flock. They should never be suffered to taste the flesh of a carrion sheep lest the relish should tempt them to indulge in such food again. They may be fed also broth made out of bones, or bones themselves when broken up, for that makes their teeth stronger and the mouth wider: and thereby the jaws are stretched, while the zest of the marrow makes the dog fiercer. They should be accustomed to take their food in the day time where the flock is feeding and at night where the flock is folded.