The wide difference between the two characters, the slowness and want of energy of the Spartans as contrasted with the dash and enterprise of their opponents, proved of the greatest service, especially to a maritime empire like Athens. Indeed this was shown by the Syracusans, who were most like the Athenians in character, and also most successful in combating them.
Thucydides (1978). “The history of the Peloponnesian War: illustrated with maps from the 1820 Oxford edition”