by St. Macarius the Great
From St. Macarius the Egyptian, Word 7, Ch. 18
He who wishes to be an imitator of Christ, so as to become a son of God born of the Spirit, must first of all bear generously and patiently all the troubles that befall him, such as bodily illnesses, offenses, wrongs, and insults from men, and the attacks of invisible enemies; because it is by the permission of God that various temptations are allowed to holy souls, so that it may become clear which souls sincerely love God. It has ever been the mark of the Saints and Patriarchs and Prophets and Apostles and Martyrs that they went by the narrow way of trials and troubles, and so pleased God.
The soul that desires to please God needs first of all patience and hope, because one of the tricks of the devil is, in time of trouble, to make us despondent and divert us from hope and trust in God. God never allows those who trust in Him to be overwhelmed by temptations so as to reach utter exhaustion; for says the Apostle, God is faithful and He will not let you be tempted beyond your strength, but with the temptation, He will also dispose the issue of it, and enable you to bear it [I Cor. 10:13]. The devil does not worry a soul as much as he would like, but as much as he is permitted by God. If men know what weight can be borne by a horse, a donkey, or a camel, and load them accordingly; if a potter knows how long vessels must be kept in the fire so as not to be cracked by being baked longer than necessary and so as not to be unfit for use through being taken out of the fire too soon – if in a man their so much knowledge, then how much more and incomparable more does the wisdom of God know the amount of temptation each soul must bear so that, by being tested by it, it may become capable of inheriting the Kingdom of Heaven.