Perhaps the subject which caused the most discussion was the attempt to determine a criterion of truth. Soon after the time when they broke away from the ancient religious faith, the thinkers of Greece began to doubt the ability of the mind to ascertain absolute truth. This arose out of the imperfections of knowledge obtained through the senses. Sense perception {227} was held in much doubt. The world is full of delusions. Man thinks he sees when he does not. The rainbow is but an illusion when we attempt to analyze it. The eye deceives, the ear hears what does not exist; even touch and taste frequently deceive us. What, then, can be relied upon as accurate in determining knowledge? To this the Greek mind answers, "Nothing"; it reaches no definite conclusion, and this is the cardinal weakness of the philosophy. Indeed, the great weakness of the entire age of philosophy was want of data. It was a time of intense activity of the mind, but the lack of data led to much worthless speculation. The systematic method of scientific observation had not yet been discovered. But how could this philosophical speculation affect civilization? It determined the views of life entertained by the Greeks, and human progress depended upon this. The progress of the world depends upon the attitude of the human mind toward nature, toward man and his life. The study of philosophy developed the mental capacity of man, gave him power to cope with nature, and enhanced his possibility of right living. More than this, it taught man to rely upon himself in explaining the origin and growth of the universe and the development of human life. Though these points were gained only by the few and soon lost sight of by all, yet they were revived in after years, and placed man upon the right basis for improvement. The quickening impulse of philosophy had its influence on art and language. The language of the Greeks stands as their most powerful creation. The development of philosophy enlarged the scope of language and increased its already rich vocabulary. Art was a representation of nature. The predominance given to man in life, the study of heroes and gods, gave ideal creations and led to the expression of beauty. Philosophy, literature, language, and art, including architecture, represent the products of Greek civilization, and as such have been the lasting heritage of the nations that have followed. The philosophy and practice of social life and government {228} received a high development in Greece. They will be treated in a separate chapter. SUBJECTS FOR FURTHER STUDY 1. What was the importance of Socrates' teaching? Why was he put to death? 2. What has been the influence of Plato's teaching on modern life? 3. Why is Aristotle considered the greatest of the Greeks? 4. What was the influence of the library at Alexandria? 5. What caused the decline in Greek philosophy?