The Athenian government was said to be the the first government to apply democracy. Athenians voted by raising their hands during meetings. Hence, at that early era, they already have a concept of valuing the opinions of every member of the government. The answer is: use of juries to decide trials.
An influential aspect of Athenian government on modern democracies is the use of juries to decide trials. the creation of written laws. the presumption of innocence. the belief in equality.