St. Maximos the Confessor: The person who has come to know the weakness of human nature...

The person who has come to know the weakness of human nature has gained experience of divine power. Such a man, having achieved some things and eager to achieve others through this divine power, never belittles anyone. 

For he knows that just as God has helped him and freed him from many passions and difficulties, so, when God wishes, He is able to help all men, especially those pursuing the spiritual way for His sake. And if in His providence He does not deliver all men together from their passions, yet like a good and loving physician He heals with individual treatment each of those who are trying to make progress.

St. Maximos the Confessor