Not external things, but internal, advance or injure a man, namely the Spirit of grace or the spirit of wickedness.
1. Suppose there is a great city, and it is deserted, the walls all broken down, and it be taken by enemies, its greatness is of no use. Care then must be taken in proportion to its greatness that it should have strong walls, that the enemy may not come in. In like manner, souls adorned with knowledge and intelligence and acuteness of mind are like great cities. But careful inquiry must be made whether they are fortified with the power of the Spirit, lest the enemy should get into them and lay them waste. The wise men of the world, Aristotle, or Plato, or Socrates, being prudent in knowledge, were like great cities, but they were made waste by enemies, because the Spirit of God was not in them.
2. But as many simple folk as are partakers of grace are like little cities fortified by the power of the cross. They only fall from grace for two causes, and perish either because they cannot bear the afflictions that are brought upon them, or because, having tasted the sweets of the pleasures of sin, they continued in them. Those who tread the way cannot go through without temptations. As in childbirth the beggar and the queen have the same pangs, and as the rich man’s land and the poor man’s alike, if they receive not the necessary culture, cannot bear worthy fruits, so in the culture of the soul not the wise man, not the rich man, reigns in grace, unless through endurance, and afflictions, and many a labour. The life of Christians ought to be of that kind. As honey, being sweet, does not admit of anything bitter or poisonous, so Christians are good to all who come near them, good or bad, as the Lord says, Be ye good, like your heavenly Father. The thing that injures and pollutes a man is from within. Out of the heart proceed evil thoughts, as the Lord says; because the things which defile the man are from within.
3. From within, creeping and advancing in the soul, is the spirit of wickedness, calculating, inciting, which is the veil of darkness, the old man, which those who flee to God must put off, and put on the heavenly, new man, which is Christ. Nothing outside can hurt a man, only the spirit of darkness dwelling in the heart, alive and active; so that every one in his thoughts ought to possess the conflict, that Christ may shine upon his heart. To whom be glory for ever. Amen.