This chapter talks about the legal relationship between foreign birth and Athenian citizenship in Aristophanes' time. Athenian citizenship was given to the Plataians who settled in Athens after the fall of Plataia in 427. There were some individual foreigners who were given citizenship in return for outstanding services to Athens or for diplomatic reasons. Perikles' law about citizenship, and unfortunately some aspects of it are very controversial. The rule in some Greek cities was that a free man had the same status as his father: if his father was a citizen, he was a citizen, and if not, not. The problem about the law of Perikles is whether it forbade or invalidated marriage between an Athenian and a foreigner. Was the son of an Athenian man and a foreign woman simply an alien, or was he also illegitimate. There is no evidence about this for the time of Perikles, and some scholars hold that Perikles said nothing about marriage.