It is the Year of Faith and the great mystics help us see dimensions of faith that raise our hearts above ordinary existence while also rooting us more deeply in the truth. To this end, one of the newest doctors of the Church wrote about the virtue faith extensively. One aspect that he describes is the need to believe what we do not understand.
In "Listen, O Daughter" chapter 38 he mentions an analogy: just as God's love demands we renounce our self-love, and just as trust in God demands we renounce our trust in ourselves, so too the obedience we owe the truth of God demands we renounce our own opinion. This does not mean that our faith is not intelligible or that we should not try with all our might to understand the truth given to us by God, but it does mean that as Christians we do not live within the narrow confines of what we understand. Instead, we believe, we live, we stive to be faithful on the vast horizons of all that really is and this truth is always more than we understand.
St. John of Avila is inviting us to live with our minds bent in adoration, our intellects bowed down in humility before a mystery so immense and beautiful and moving that only a light beyond all natural lights, the light that comes from God - the Light that shines in the darkness - can allow us to glimpse its inexhaustible glory - a glory which is known by love informed faith alone.