We must continually protect our heart from unclean thoughts and impressions, according to the words of the author of the book of Proverbs: "Keep thy heart with all diligence; for out of it are the issues of life" (Prov. 4:23).
Purity is born within the heart from extended safekeeping of it, to which the vision of the Lord has access, according to the assurance of eternal Truth: "Blessed are the pure in heart, for they shall see God" (Mt. 5:8).
We should not reveal unnecessarily what is best in the heart, for only then does that which has been accumulated remain in safety from enemies visible and invisible, when it is kept as a treasure in the innermost heart. Do not open the secrets of your heart to everyone.
St. Seraphim of Sarov
