Wherefore let him that thinketh he standeth take heed lest he fall (I Corinthians 10:12).

The Apostle who gives such advice knew human nature and all its weakness perfectly. Day after day, this experience is confirmed: as soon as a man straightens up from the mud of sin, he sways and falls again. As soon as he is cured of the sin of avarice, he falls into the vice of vainglory. Or, as soon as he extends his hand to help a poor man, pride topples him to the other side. Or, as soon as he becomes accustomed to prayer, he opens wide his mouth to degrade those who are not yet accustomed to prayer. Or, as soon as he feels that the Spirit of God is directing him to the path of salvation, he immediately sets himself up as a teacher to the entire world until, unfortunately, through this he completely drives the Spirit from himself.

— The Prologue of Ohrid by St. Nikolai Velimirovic (Page 40)