I learnt by experience, but little more than four years ago, that our thoughts, or it is clearer to call it our imagination, are not the same thing as the understanding.
I questioned a theologian on the subject; he told me it was the fact, which consoled me not a little.
As the understanding is one of the powers of the soul, it puzzled me to see it so sluggish at times, while, as a rule, the imagination takes flight at once, so that God alone can control it by so uniting us to Himself that we seem, in a manner, detached from our bodies.
It puzzled me to see that while to all appearance the powers of the soul were occupied with God and recollected in Him, the imagination was wandering elsewhere.
…We cannot stop the revolution of the heavens as they rush with velocity upon their course, neither can we control our imagination.
When this wanders we at once imagine that all the powers of the soul follow it; we think everything is lost, and that the time spent in God’s presence is wasted.
Meanwhile, the soul is perhaps entirely united to Him in the innermost mansions, while the imagination is in the precincts of the castle, struggling with a thousand wild and venomous creatures and gaining merit by its warfare.
Therefore we need not let ourselves be disturbed, nor give up prayer, as the devil is striving to persuade us. As a rule, all our anxieties and troubles come from misunderstanding our own nature.
Teresa of Avila (1515-1582): Interior Castle 4,1,8-9.