Plato (especially as developed in Neo-Platonism) and Aristotle. These two philosophies not merely affected the thinking of Jew and Mohammedan but really transformed it from religious and ethical discussions into metaphysical systems. In the Bible and similarly in the Koran we have a purely personal view of God and the world. God is a person, he creates the world—out of nothing to be sure—but nevertheless he is thought of doing it in the manner in which a person does such things with a will and a purpose in time and place. He puts a soul into man and communicates to him laws and prohibitions. Man must obey these laws because they are the will of God and are good, and he will be rewarded and punished according to his attitude in obedience and disobedience. The character of the entire point of view is personal, human, teleological, ethical. There is no attempt made at an impersonal and objective analysis of the common aspects of all existing things, the elements underlying all nature. Nor is there any conscious effort at a critical classification of the various kinds of things existing in nature beyond the ordinary and evident classification found in Genesis—heaven and earth; in heaven, sun, moon and stars; on earth, grass, fruit trees, insects, water animals, birds, quadrupeds, man. Then light and darkness, the seasons of the year, dry land and water.
In Greek philosophy for the first time we find speculations concerning the common element or elements out of which the world is made—the material cause as Aristotle later called it. The Sophists and Socrates gave the first impulse to a logical analysis of what is involved in description or definition. The concept as denoting the essence of a thing is the important contribution Socrates made to knowledge. Plato objectified the concept, or rather he posited an object as the basis of the concept, and raised it out of this world of shadows to an intelligible world of realities on which the world of particulars depends. But it was Aristotle who made a thoroughgoing analysis of thing as well as thought, and he was the master of knowledge through the middle ages alike for Jew, Christian and Mohammedan.
First of all he classified all objects of our experience and found that they can be grouped in ten classes or categories as he called them. Think of any thing you please and you will find that it is either an object in the strict sense, i. e., some thing that exists independently
