There is a famous saying in "The Art of War", the world's first military book: "Know your enemy and yourself, and you will never be in danger in a hundred battles." It can be seen that Sun Wu, known as the "originator of Eastern military science", has very clearly realized the "knowing the enemy" very early on. "The inner connection and implementation sequence of "war". That is to say, "knowledge" and "war" are an inseparable unity. Only by "knowing the enemy and knowing yourself" can we "win a hundred battles without danger". As Guan Zhong, a military strategist in the Spring and Autumn Period, said: "If you don't know the enemy's politics, you can't add to it; if you don't know the enemy's feelings, you can't make an appointment; if you don't know the enemy's generals, you can't lead the army; if you don't know the enemy's men, you can't show them first. "The so-called "knowledge" and "knowledge" are actually espionage and intelligence activities, and they obviously serve the war. Therefore, war is the breeding ground of spies, and spies are the products of war. Therefore, to explore the origins and causes of espionage, we must first trace the origins of war.

War is called "fighting" or "defeating" in oracle bone inscriptions. It is also called "war", "bing", "rong", "conquest", etc. The word "war" was first seen in the Warring States Period. The book "Wu Zi's Art of War" from the period. According to historical records, the earliest war in China was the "War at the End of Primitive Society" (about 5,000 years ago). Such as "The Battle of Shennong's Cutting Axes and Firearms"; "The Battle of Zhuolu between Huangdi and Chiyou"; "Yao attacked the real situation and peeked at the intentions of his neighbors to avoid blind actions. Under such specific historical conditions and the specific needs of the war," The eternal truth of "knowing the enemy and knowing yourself" naturally sprouted in the practice of war. And the task of "knowing the enemy" must be carried out by dedicated people, and such people are spies. The Battle of Doudanshui " and "The Battle between Shun and Yu against Sanmiao" and so on. In the "Battle between Shun and Yu against Sanmiao", Yu raised troops to attack based on the intelligence that "Sanmiao was ready to move and had evil intentions". According to the "Zuo Zhuan: The Seventh Year of Ai Gong", when Yu united the princes in Tushan, "all the nations were holding jade and silk." "Marriage in the morning, enemies in the evening", "Allies openly, enemies secretly" are complex, confusing and changeable situations, which make all parties involved in or watching the war who "use stones as soldiers" try their best to detect the enemy. Fang's reality.