Isaac of Nineveh

Some of his [humanity’s] petitions God grants him promptly (I mean those without which no one can be saved), but some He withholds from him. And on certain occasions He restrains and dispels from him the scorching assault of the enemy, while on others, He permits him to be tempted, that this trial may become to him a cause for drawing near to God (as I said before), and also that he may be instructed and have the experience of temptations. And such is the word of Scripture: “The Lord left many nations, without driving them out; neither delivered He them into the hands of Jesus [Joshua], the son of Navi, to chastise the sons of Israel by them, and that the tribes of the sons of Israel might be taught, and learn war.” For the righteous man who has no consciousness of his own weakness walks on a razor’s edge, and is never far from falling, nor from the ravening lion—I mean the demon of pride. And again, a man who does not know his own weakness falls short of humility; and he who falls short of this, also falls short of perfection; and he who falls short of perfection is forever held by dread, because his city is not founded on pillars of iron, neither upon lintels of brass, that is, humility.