Why do we purify the heart? It is the chosen dwelling place of God. It is the "palace of Christ in which he retires" (St. Macarius). It is the very seat of eternity, the gateway between heaven and earth---the Holy of Holies. If your heart is like a house where clutter (beautiful and good things as well as ugly and evil things) is the rule, then all that's holy is hidden, covered, and ignored.  Tragic . . . for you can know so much more.

The key is not merely to get rid of the clutter, but to become so unattached to it (and that which causes you to love it and keep it around), so that you no longer feel compelled to have it around anyway.

This is the fruit of interior prayer---that watchfulness, awareness, and non-attachment to thought-clutter that comes from continual, unceasing returning to Christ in prayer.

Cleaning the house, purifying the heart, make it more hospitable to the indwelling of Grace.   Nonattachment keeps it open and pleasing to the fullness of the Trinity of love.