All of the letters are spurious.[10] The first nine probably date from the 3rd century BC, they are usually included among the Cynic epistles, and reflect how the Cynic philosophers viewed him as prefiguring many of their ideas;[10] the tenth letter is quoted by Diogenes Laërtius, it is addressed to Croesus, the proverbially rich king of Lydia, it too is fictitious: