When and how the fables arrived in and travelled from ancient Greece remains uncertain. Some cannot be dated any earlier than Babrius and Phaedrus, several centuries after Aesop, and yet others even later. The earliest mentioned collection was by Demetrius of Phalerum, an Athenian orator and statesman of the 4th century BCE, who compiled the fables into a set of ten books for the use of orators. A follower of Aristotle, he simply catalogued all the fables that earlier Greek writers had used in isolation as exempla, putting them into prose. At least it was evidence of what was attributed to Aesop by others; but this may have included any ascription to him from the oral tradition in the way of animal fables, fictitious anecdotes, etiological or satirical myths, possibly even any proverb or joke, that these writers transmitted. It is more a proof of the power of Aesop's name to attract such stories to it than evidence of his actual authorship. In any case, although the work of Demetrius was mentioned frequently for the next twelve centuries, and was considered the official Aesop, no copy now survives. Present day collections evolved from the later Greek version of Babrius, of which there now exists an incomplete manuscript of some 160 fables in choliambic verse. Current opinion is that he lived in the 1st century CE. The version of 55 fables in choliambic tetrameters by the 9th century CE Ignatius the Deacon is also worth mentioning for its early inclusion of tales from Oriental sources.