Who wrote the book Eye of the Earth?

It is generally acknowledged that it was written by Elder Gu Tuo in the Northern Song Dynasty.

Elder Gu Tuo, also known as Jing Dao Monk, was born in the early years of the Northern Song Dynasty and is an influential scholar of geomancy. His birth date, death date and life story are unknown.

It summarizes Feng Shui in five words: dragon, cave, sand, water and direction. That is to say, dragons should be dominated by ups and downs, sand should be wrapped around acupoints to protect them clearly, acupoints should be hidden by qi veins, water should be collected horizontally against the direction, and water should stand against the water. These 50 words are the core of all the books in "Kanyu", which are really concise and point to the truth.