Purity of heart consists in the nous being free from evil thoughts, from which evil and passionate feelings originate which cause the body to be passionately excited. For it is then that both soul and body are defiled, and to a certain degree their purity and spotlessness are lost.
The first evil and passionate thought but primarily the corresponding passionate fantasy, is the starting point of all forms of sin. No sin occurs in deed if an evil thought does not precede it by means of the imagination. Therefore, in order to attain the greatest good, purity in the full sense of the word, we need to purify our nous from sinful imaginations and thoughts. Only in this way is purity acquired with a firm foundation.
If we want to stop doing evil deeds without paying attention to our inward thoughts, we labor in vain. When we have taken care to purify our soul, the God of glory will dwell in it and it will become His holy and luxurious temple, giving forth the fragrance of the incense of unceasing prayer to Him.
Elder Ephraim of Arizona
