In the year 507 B.C., an Athenian leader Cleisthenes introduced a system of political reforms that he called demokratia, or “rule by the people” It was the first known democracy in the world. This new system of democracy was enforced, where citizens could vote directly on bills, legislation, and motion. However, only approximately 10% - 20% of the population in Greece were actually considered citizens, meaning only that small percentage had a say. Those that were unable to vote were children, women, foreigners, and slaves. While this event, unfortunately, did not include everyone, it was a step forward to creating an individualistic society.
Contribution to the development of classical liberalism:
Ancient Greek Democracy isn't quite an accurate representation of Classical Liberalism. However, this was a significant time as some people - specifically "adult, male citizen[s] who owned land," - were finally given the opportunity to have a voice.
One of the key principles of classical liberalism is the belief that humans are ready and reasonable to make these decisions that will benefit not only themselves but also society.
Ancient Greek democracy was the very first to partake in this way of living, setting the foundation for the later development of classical liberalism.