Essentially, to know God's will our hearts must be clean and clear, able to see directly in the light of the Gospel. This does not happen over night, nor is it entirely our work. But we can set up structures to support the seed of holiness planted in our hearts.
Regular examination is key. Not neurotic navel-gazing, nor the narcissistic self-perfecting of our ego, it remains the sole means of clarifying our thinking. Quiet reflection on the grace of God in my today teaches me who I am and who he calls me to be.
It can degenerate. It can become destructive. But the power of self-knowledge empowers me to choose minute by minute to give my life over to God’s direction.
The Holy Spirit then takes over the process. We cannot cleanse our hearts from the darkness that hides in the corners, behind the scenes, in the background. Only his light penetrating into every part of our lives can begin to illumine and then purify our hearts completely.
Miserere nobis, Domine...