For the Providence of God is beyond our ken and comprehension, while our reasonings and actions and the future are revealed to His eyes alone.
And by “all” I mean those that are not in our hands: for those that are in our power are outside the sphere of Providence and within that of our Free-will.
Now the works of Providence are partly according to the good-will [κατ᾽ εὐδοκίαν] of God and partly according to permission [κατὰ συγχώρησιν].
Works of good-will include all those that are undeniably good, while there are many forms of concession.
For Providence often permits the just man to encounter misfortune in order that he may reveal to others the virtue that lies concealed within him, as was the case with Job (Job 1:11).
At other times it allows something strange to be done in order that something great and marvellous might be accomplished through the seemingly-strange act, as when the salvation of men was brought about through the Cross.
In another way it allows the pious man to suffer sore trials in order that he may not depart from a right conscience nor lapse into pride on account of the power and grace granted to him, as was the case with Paul (2 Cor. 2:7).
One man is forsaken for a season with a view to another’s restoration, in order that others when they see his state may be taught a lesson, as in the case of Lazarus and the rich man (Luke 16:19). For it belongs to our nature to be cast down when we see persons in distress.
Another is deserted by Providence in order that another may be glorified, and not for his own sin or that of his parents, just as the man who was blind from his birth ministered to the glory of the Son of Man (John 9:1).
Again another is permitted to suffer in order to stir up emulation in the breasts of others, so that others by magnifying the glory of the sufferer may resolutely welcome suffering in the hope of future glory and the desire for future blessings, as in the case of the martyrs.
Another is allowed to fall at times into some act of baseness in order that another worse fault may be thus corrected, as for instance when God allows a man who takes pride in his virtue and righteousness to fall away into fornication in order that he may be brought through this fall into the perception of his own weakness and be humbled and approach and make confession to the Lord.
John Damascene (c.675-749): De Fide Orthodoxa 2, 29.