On Horsemanship (Περὶ ἱππικῆς, peri hippikēs) has been written by Xenophon around 350 B.C. and is known as the first book ever written on the subject of horses, their selection, care and training. One text is more ancient (written by Kikkuli of the Mitanni Kingdom) but clearly not as complete as this one.
It is quite interesting to observe that most of the major principles on which modern Natural Horsemanship is based were already well known more than two thousand years ago in Greece and around the Mediterranean Sea. Indeed, the philosopher Xenophon clearly deals with the following concepts:

• Desensitizing;
• Gentleness and patience;
• Timing and harmony with horses;
• Diversity in training;
• Making the wrong thing difficult and the right thing easy;
• Getting the soft feel and avoiding riding gimmicks;
• Rewarding the slightest try.