When you see the word "ancient," you probably think of something old and outdated. But you might be surprised that many ideas and institutions from ancient Greece still exist today. We have the ancient Greeks to thank for things like democracy, libraries, the modern alphabet, and even zoology. Here are some notable Greeks and how they helped to shape our world. Socrates Socrates was one of the most famous ancient Greek philosophers. He spent the majority of his life asking questions about the world. He is responsible for developing what is known as the Socratic method, which is still used in law schools today. Instead of lecturing, professors ask students a series of questions. These questions are meant to help students think critically and understand the ideas that might influence how they see each case. Socrates did not leave a written record of his life or ideas. Most of what we know about Socrates came from one of his students, Plato. Plato Thanks to Plato, we know a lot about Socrates. Nevertheless, Plato made his own important contributions. Born around 427 B.C.E., Plato, who was a well-known writer, would be a major influence on ideas in Europe and the United States. One of his most famous writings is "The Republic." In it, Plato examines justice, its role in our world and its relationship to happiness. These were all themes familiar to the Founding Fathers of the United States. Plato is also famous for being the teacher of another important philosopher, Aristotle. Aristotle Aristotle is still considered to be one of the greatest thinkers in the areas of politics, psychology, and ethics–the study of what is right and wrong. He wrote about 200 works during his lifetime. Aristotle gave much thought to the meaning of life and what it means to live a moral life. Immensely curious, he also studied animals and tried to classify them into different groups. He created the foundation for zoology, the study of animals and their behavior. Through his writing about the soul, Aristotle laid the foundation for psychology, the scientific study of the human mind and how it affects behavior. He taught King Philip II of Macedon's son, Alexander, who would later come to be known as Alexander "the Great." Alexander the Great Born to King Philip II, Alexander III of Macedon proved early on that he was destined for greatness. At a young age, Alexander learned to fight and ride and tamed the wild horse Bucephalus at age 12. Only a few years later, when he was 18, Alexander got his first chance to fight in a war. Soon after, he took over his father's throne and continued to prove himself to be a strong and able military commander. Alexander eventually created an empire stretching from Macedon, an ancient Greek kingdom, across the entire Middle East to the frontiers of India. By 323 B.C.E., Alexander ruled over an enormous amount of land. Historians nicknamed him Alexander "the Great." Pericles At the other end of ancient Greece was another strong leader who lived during the golden age of Athens. His name was Pericles. Pericles, who lived about 100 years before Alexander, came from an important family in Athens and had a war hero for a father. Pericles did much to help the culture of Athens thrive. He helped to pay for the Parthenon, a temple dedicated to the goddess Athena that still stands today. Pericles was one of Athens' leading statesmen and generals. Like Alexander, Pericles also led many successful military campaigns. Pythagoras Greek philosophers and military commanders definitely left their mark on the world, but there were also famous mathematicians whose ideas are still used today. If you have ever tried to find the area of a right triangle, you have likely used the Pythagorean theorem, for example. The equation is named after the mathematician Pythagoras. This early mathematician used numbers and mathematics to seek meaning in life. He even created a religious order in which the members focused on philosophy and math. Hippocrates Modern medicine has been heavily influenced by the work of Hippocrates, an ancient Greek physician. His methods were written down in 60 medical books. He recommended a healthy diet and exercise. He also said it was important to record case histories and treatments, which is now an essential practice in modern medicine. Hippocrates is best known for the Hippocratic oath, a list of ethical guidelines that new doctors promise to follow. The most famous part of the Hippocratic oath is "Do no harm." These Greeks lived thousands of years ago, but their ideas helped us to build the thriving world in which we live today.