There is also a difference of opinion with respect to their number. Leander inserts in the number instead of Cleobulus and Myson, Leophantus Gorsias, a native of either Lebedos or Ephesus; and Epimenides, the Cretan; Plato, in his Protagoras, reckons Myson among them instead of Periander. And Ephorus mentions Anacharsis in the place of Myson; some also add Pythagoras to the number. Dicæarchus speaks of four, as universally agreed upon, Thales, Bias, Pittacus, and Solon; and then enumerates six more, of whom we are to select three, namely, Aristodemus, Pamphilus, Chilo the Lacedæmonian, Cleobulus, Anacharsis, and Periander. Some add Acusilaus of Argos, the son of Cabas, or Scabras. But Hermippus, in his Treatise on the Wise Men says that there were altogether seventeen, out of whom different authors selected different individuals to make up the seven. These seventeen were Solon, Thales, Pittacus, Bias, Chilo, Myson, Cleobulus, Periander, Anacharsis, Acusilaus, Epimenides, Leophantus, Pherecydes, Aristodemus, Pythagoras, Lasus the son of Charmantides, or Sisymbrinus, or as Aristoxenus calls him the son of Chabrinus, a citizen of Hermione, and Anaxagoras. But Hippobotus in his Description of the Philosophers enumerates among them Orpheus, Linus, Solon, Periander, Anacharsis, Cleobulus, Myson, Thales, Bias, Pittacus, Epicharmus, and Pythagoras. XV. The following letters are preserved as having been written by Thales:— THALES TO PHERECYDES. I hear that you are disposed, as no other Ionian has been, to discourse to the Greeks about divine things, and perhaps it will be wiser of you to reserve for your own friends what you write rather than to entrust it to any chance people, without any advantage. If therefore it is agreeable to you, I should be glad to become a pupil of yours as to the matters about which you write; and if you invite me I will come to you to Syros; for Solon the Athenian and I must be out of our senses if we sailed to Crete to investigate the history of that country, and to Egypt for the purpose of conferring with the priests and astronomers who are to be found there, and yet are unwilling to make a voyage to you; for Solon will come too, if you will give him leave, for as you are fond of your present habitation you are not likely to come to Ionia, nor are you desirous of seeing strangers; but you rather, as I hope, devote yourself wholly to the occupation of writing. We, on the other hand, who write nothing, travel over all Greece and Asia. THALES TO SOLON.