A Patristic View of Signs and Wonders
The Lord Who is always near His saints through the help He sends to them does not show, without necessity, His power manifestly by performing any perceptible sign, lest the things that are meant to help us should become impotent or a means to bring us harm. Such is His way, though...His secret providence does not abandon them one moment.
...As long as possible He strengthens them secretly in order that they may remain standing before that difficulty. By the knowledge which He grants them, He causes its bonds to be loosened, and by contemplation He excites them unto glorification, in order that the matter may be of profit to both parties.
If however the case wants manifest action, He will proceed to give this for necessity's sake. His acts of providence are wise, serving necessity, not chance.
He that without necessity ventures upon this, begging from God and desiring that wonders and powers should happen through himself, is found to be tempted of the scornful demon in his heart, and even a boaster and one sick in heart...That a man should desire thus wilfully, without necessity, is apostasy from watchfulness and aberration from true knowledge...[T]hose who are truly righteous do not desire this; and they not only do not count upon this but they do not even ask for it, if it is given them; neither before the eyes of men, nor even privately.
Unto one of the saints, because of his serenity, the gift was granted that he knew beforehand if any one should visit him; but he asked God, and he persuaded others to pray for this, that the gift might be taken away from him.