The Link between Pure Love and Clear Vision

“The key to discerning God’s will is not intellectual but volitional. The heart is the head’s educator here. The secret of discernment is “ordo amoris”[or] “the order of love.”
If we do not have this proper order of love, if we upset the hierarchy of things and love some mere thing instead of God at the center of our lives, then this first and fundamental error will generate a second.” We will develop an obsession with whatever idol we have put in God’s place. No one can treat God as a creature without also treating some creature as God, for we are made with both creature-shaped holes and God-shaped holes in us. We cannot live without filling them. The trouble is, the real God won’t fit into the creature-shaped hole, so we have to trim God down to our size. And a creature won’t fill up the God-shaped hole, so we have to keep running to more and more creatures to try to plug the gap. It is like trying to fill the Grand Canyon with marbles.
The process of living creatures as if they were God, trying to fill the God-hole with creature-pegs, always becomes obsessive because we cannot stop and cannot succeed. Obsession always clouds the mind. On bit of beclouding that always happens during this process is that we see God as an outside interferer, someone who is always trying to spoil our fun and smash our toys (our idols). The things that were innocent when subordinated to God become temptations and tugs of war between God and me when I put them in God’s place.
But it is hard to discern this when clouded by lust or greed or resentment or envy or sloth or any of the Seven Deadly Sins. We must always hold the line firm on the first battlefield, which is the battlefield of the mind. We must always think of first things first. Then second things will fall into place. We will see the temptation to idolize those second things for what it is: sheer folly. Even if we succumb to temptation and sin, let us not see it as anything but folly. Let us not rationalize and becloud our own minds to make the guilt go away. Guilt is like pain: a necessary built-in warning device to head us away from the harmful thing that triggers it. Of course, both guilt and pain sensors can become either oversensitive or under sensitive. But they are there for a natural and necessary purpose.
So we must not rationalize. We must reason rightly. We must see things in their proper and real perspective if we are to live well. But the key to this seeing, in turn is loving things rightly. If we over-love things, we tend to over-value them in our minds in order to rationalize our over-valuing of them in our lives. If we under-love God and people, we tend to undervalue them in our minds to rationalize undervaluing them in our lives. …Thus loving and seeing depend on each other. If I do not love properly, it clouds my vision. And if my vision in clouded, I will not love aright.
This sounds complicated, but it is simple when we live it. Say I want to take revenge on someone. God forbids this. Therefore I see God as a bother. But if I first loved God, I would then see that revenge was the bother. When I am in the grip of lust, God appears as a puritanical interferer. But when I am in the grip of God’s love, lust appears as it truly is: a pale perversion of true love and joy.
It starts in the will. If your will is right, if your will is set on “the one thing needful,” if your will is determined to obey the first and greatest commandment, then you will be able to understand, to discern, and to see. …
If, on the other hand, you do not love Him, then no matter how clever you are, you are bound to misunderstand Him and His commands as threatening to what you love.”

Peter Kreeft in The God Who Loves You (from the chapter “God’s Love in Practical Theology”)