"Blessed are they that mourn." It is one thing to believe the theory that I am spiritually a poverty-stricken pauper, it is quite another to have an acute sense of it in my soul. Where the latter exists, there are deep exercises of heart, which evoke the bitter cry, "my leanness, my leanness, woe unto me!" (Isa. 24:16). There is deep anguish that there is so little growth in grace, so little fruit to God’s glory, such a wretched return made for His abounding goodness unto me. This is accompanied by an ever-deepening discovery of the depths of corruption which is still within me. The soul finds that when it would do good, evil is present with him (Rom. 7:21). It is grieved by the motions of unbelief, the swellings of pride, the surging of rebellion against God. Instead of peace, there is war within; instead of realizing his holy aspirations, the blessed one is daily defeated; until the stricken heart cries out, "O wretched man that I am! who shall deliver me from the body of this death?" (Rom. 7:24)."

A. W. Pink The Nature and Basis of Assurance

A Tulip Not a Daisy