Anshin (安心)
The term "anshin," also referred to as anjin, means a state of mind in which there is nothing to be concerned about and one feels calm and easy. As previously noted, it was originally pronounced as 'anjin,' but it has been pronounced 'anshin' since the Edo period.
Summary
It is originally an abbreviation of the term "anjin ryumyo" which means knowing the will of heaven and keeping one's mind peaceful, or submitting one's fate to the will of heaven and keeping always calm in Confucianism. In the Zen sect, the term is still used for being released from fear and anxiety, attaining a state of enlightenment and spiritual peace to establish one's independence by teachings of Buddha. The term is said to have been used by Daruma (Bodhidharma) for the first time in Buddhism. Fear and anxiety arise from Bonno (earthly desires) originating in one's wants. For this reason, attaining the state of enlightenment is said to have been a proof of faith and religious belief.
Jodo (Pure Land) sect
In the Jodo sect, the term "anshin" means believing without a doubt in salvation by Amida Buddha and wishing for gokuraku ojo (peaceful death) by the Pure Land teachings. It is divided into three kinds of mind, that is, Sanshin (Three minds). They are Shijoshin (utterly sincere mind) to wish to be reborn in the Pure Land earnestly, Jinshin (profound mind) to wish strongly, and Eko hotsugan shin (belief in the rebirth of oneself in the Pure Land in the future) to dedicate kudoku (merit) and to wish to be reborn in the Pure Land. It is believed that a person having these three minds is sure to be reborn in the Pure Land. In Shodo-mon (the ordinary schools of the way of holiness by the processes of devotion), the term "anshin" means calming oneself, which is used in a similar sense to that in the Zen sect.