The two main groups of letters are a set of 51 letters attributed to
Diogenes of Sinope, and a set of 36 letters attributed to
Crates of Thebes. Most of the letters of Diogenes were probably written or altered in the 1st century BCE, whereas the letters of Crates, some of which seem to be based on the Diogenes letters, probably date from the 1st century CE. It is not known who wrote the letters, but they seem to have been influenced by multiple authors. Written in
Koine Greek, the Epistles are among the few Cynic writings which have survived from the time of the Roman empire. In addition to these letters, there are 10 spurious epistles attributed to
Anacharsis and 9 epistles attributed to
Heraclitus. The letters of Anacharsis may have been written in the 3rd century BCE, whereas the Heraclitean letters probably date from the 1st century CE. Anacharsis and Heraclitus predate the Cynics, but they were both regarded by the Cynics to have anticipated Cynic ideals. There are also 35
Socratic epistles supposedly written by
Socrates and his followers (
Antisthenes,
Aristippus,
Aeschines,
Xenophon, etc.). Many of these letters were also written by someone with a strong affinity towards Cynic ideals, albeit with a sympathy towards Aristippus rather than Antisthenes. Other fictitious letters, such as some of those attributed to
Hippocrates, could also be included among the Cynic epistles. ==Content==