From the point of view of Artificial Intelligence, the most interesting aspect of Aristotle's work is his study of logic. He invented the idea of the syllogism, which he defined as follows: "A discourse in which certain things having been stated, something else follows of necessity from their being so."Aristotle's logic was developed and expanded on by later philosophers, mathematicians, and logicians. The first real steps in the study of logic after Aristotle took place in the 12th century. Although Artificial Intelligence is one of the newest fields of intellectual research, its foundations began thousands of years ago. In studying Artificial Intelligence, it is useful to have an understanding of the background of a number of other subjects, primarily philosophy, linguistics, psychology, and biology. Perhaps a better starting point would be to ask, "What is intelligence?" This is a complex question with no well-defined answer that has puzzled biologists, psychologists, and philosophers for centuries. This Monograph discussed some excellent engineering and applications of AI.