The ancients found that thoughts are powerful things. They learned that good thoughts and bad are equally potent. Some of them were persistently curious enough to learn that when they re-positioned their thoughts, they could eliminate physical, as well as mental, intrusion.
This took practice. They began to devote themselves to a system of meditation that cleared their thinking of everything. When they recognized the beneficial results, they gave their practice a name. They called it “Zen,” meaning “absorption” or “meditative state.