Besides, all other birds are, so to say, never out of our eyes; they let themselves be seen of us continually; but a vulture is a very rare sight, and you can seldom meet with a man that has seen their young; their rarity and infrequency has raised a strange opinion in some, that they come to us from some other world; as soothsayers ascribe a divine origination to all things not produced either of nature or of themselves. When Remus knew the cheat, he was much displeased; and as Romulus was casting up a ditch, where he designed the foundation of the city wall, he turned some pieces of the work to ridicule, and obstructed others: at last, as he was in contempt leaping over it, some say Romulus himself struck him, others Celer, one of his companions; he fell, however, and in the scuffle Faustulus also was slain, and Plistinus, who, being Faustulus's brother, story tells us, helped to bring up Romulus. Celer upon this fled instantly into Tuscany, and from him the Romans call all men that are swift of foot Celeres; and because Quintus Metellus, at his father's funeral, in a few days' time gave the people a show of gladiators, admiring his expedition in getting it ready, they gave him the name of Celer. Romulus, having buried his brother Remus, together with his two foster-fathers, on the mount Remonia, set to building his city; and sent for men out of Tuscany, who directed him by sacred usages and written rules in all the ceremonies to be observed, as in a religious rite. First, they dug a round trench about that which is now the Comitium, or Court of Assembly and into it solemnly threw the first-fruits of all things either good by custom or necessary by nature; lastly, every man taking a small piece of earth of the country from whence he came, they all threw them in promiscuously together. This trench they call, as they do the heavens, Mundus; making which their centre, they described the city in a circle round it. Then the founder fitted to a plough, a bronze ploughshare, and, yoking together a bull and a cow, drove himself a deep line or furrow round the bounds; while the business of those that followed after was to see that whatever earth was thrown up should be turned all inwards towards the city, and not to let any clod lie outside. With this line they described the wall, and called it, by a contradiction, Pomoerium, that is, "post murum," after or beside the wall; and where they designed to make a gate, there they took out the share, carried the plough over, and left a space; for which reason they consider the whole wall as holy, except where the gates are; for had they adjudged them also sacred, they could not, without offence to religion, have given free ingress and egress for the necessaries of human life, some of which are in themselves unclean.