A bull or cow sometimes also stood on a grave. In the British Museum is a bull of this class[150]. A heifer is said to have stood on the tomb of Boidion, concubine of Chares, who followed him in his expedition against Philip of Macedon[151]. On the grave of Diogenes of Sinope was a dog, to mark his cynic nature. But the dog which appears on the summit of a tomb in the Athenian cemetery need not have anything to do with cynicism. He may have his place as a trusty watcher and guardian; or he may be connected with the cultus of the dead, as we have already suggested. On the grave of Philager his teacher, Metellus Nepos, set a raven, which Cicero declared to be most appropriate to a master who taught how to fly better than how to speak[152]. Of course the raven, as the bird sacred to Apollo, was very appropriate on the tombs of learned men. In an epitaph in the _Anthology_[153] it is said that the grave of the poet Sophocles was surmounted by a satyr, holding in his hand a female mask. As, however, we are told by other authorities that a Siren stood on his tomb, we must suppose the satyr to have surmounted a cenotaph erected to the poet by his admirers in some other city than Athens. From another epigram[154] we learn that on the grave of Plato an eagle was sculptured: here we are clearly in the realm of poetic symbolism. CHAPTER IX ATHENS AND GREECE. PORTRAITS In the Spartan group of sepulchral monuments we found one of the two fountain-heads of Greek sepulchral reliefs, springing directly out of the ancestor-worship of the Dorian race. For the other main source, which is much less religious and more artistic in origin, we turn to Athens and to Ionia. It arises out of the custom of setting up portraits of the dead.