22 But why instead of a stern reproof did our Lord speak a parable of persuasion to that Pharisee? He spoke the parable to him tenderly, that he, though froward, might unawares be enticed to correct his perversities. For the waters that are congealed by the force of a cold wind, the heat of the sun gently dissolves. So our Lord did not at once oppose him harshly, that he might not give occasion to the rebellious to rebel again. But by blandishment He brought him under the yoke, that when he had been yoked, He might work with him, though rebellious, according to His will.
Now, because Simon was proudly minded, our Lord began humbly with him, that He might not be to him a teacher according to his folly. For if that Pharisee retained the Pharisees' pride, how could our Lord cause him to acquire humility, when the treasure of humility was not under his hand? But since our Lord was teaching humility to all men, He showed that His treasury was free from every form of pride. But this was for our sakes, that He might teach us, that whatever treasuries pride enters into, it is by boastfulness that it gains access to them.
On this account let not your left hand know what your right hand does. Our Lord then did not employ harsh reproof, because His coming was of grace: He did not refrain from reproof, because His later coming will be of retribution. For He put men to fear in His coming of humility; because it is a fearful thing to fall into His hands when He shall come in flaming fire. But our Lord bestowed the most part of His helps rather by persuasion than by reproof.
For the gentle shower softens the earth and penetrates all through it: but violent rain binds and hardens the face of the earth, so that it does not receive it. For a harsh word excites wrath, and with it are bound up wrongs. And when a harsh word has opened the door, wrath enters in, and at the heels of wrath, along with it enter in wrongs.
Source: On Our Lord (New Advent)