4. Socrates appeared soon after. He was the apostle of thought. His influence in leading men to use direct and effective modes of examination and reasoning was incalculable, and has perhaps had more effect on the world than the victorious career of Alexander or of the Romans. He was followed by Plato, a disciple of his, who pushed out to further results the same principles. He is called the prince of philosophers, and has exerted a world-wide influence. He had not the simplicity and plain directness of Socrates, though his mind was more polished, and he was more learned. Some scholars, however, consider his masterpieces to indicate as powerful a mind as the world has produced. He spent twelve years in travel, and used all the means of education, and study then to be found. His works are still the delight of the most accomplished scholars. 5. Aristotle began his career in the last years of Plato. He was the tutor of Alexander the Great. He followed a different line of study, wrote on logic, or the art of reasoning, on the natural sciences, and introduced method in the exercise of the mind and in study. Herodotus, Xenophon, Thucydides, and many other great writers, artists and sculptors, lived about the same period; and thus Grecians did for the mind what the Romans did for law and government—laid down the fundamental principles which formed the basis of real progress. The free government of Athens encouraged oratory and the art of persuasion. Demosthenes was the most celebrated orator among the Greeks, and if his state had only been more powerful he would have conquered Philip of Macedon. He was indeed one of the greatest orators of all times. Cicero, among the Romans, was a writer and orator of almost equal merit. They both lived just at the downfall of the liberties of their states, and they spoke with more effect to the times after them than to their contemporaries. If they did not succeed in preserving the liberties of Greece and Rome, they made a great impression, the name of Liberty was consecrated by their noble words, and those who destroyed it made infamous by their burning invectives. When a more favorable time came for restoring it, they lived again in influence, and triumphed by the memory and record of their great patriotism and powerful eloquence.