The Xiao Zhi Guan makes the practice of Zen, a seemingly harsh and strict discipline, accessible to the lay person.  Popularly known as Beginner's Zen and The Little Samatha Vipasana Manual, this charmingly simple book of meditation has been a favorite of teachers and students of Zen from the sixth century to the present.  Its author Zhi Yi (538-597), was the founder of Tiantai Buddhism in China.