Chapter XV.
The rational nature is capable of experiencing the joy of health alone; and it is strengthened by the guiding spirit; but who is that spirit?
Give me the joy of your salvation: and strengthen me with a principal spirit (Psalm 50:14). To whom it is owed, and to whom it is returned: it is returned to the rational nature by the joy of salvation. Joy and gladness, however, are the fruits of the Spirit. The firmament of our principal spirit is also firm. Finally, he who is confirmed by the principal spirit is not subject to servitude, does not know how to serve sin, does not waver, does not wander, nor does he vacillate with uncertainty; but being strengthened in the rock, he is firmly established in a solid footing.
Whom do we think is called the principal spirit? Many think that the right spirit refers to the Lord Jesus, who has taken away the sin of the world and has renewed the whole human race by the shedding of his own blood. And therefore it is said: Renew a right spirit within me. But they understand the holy spirit of truth: but the Holy Spirit, they believe, is the principal one, God the Father. However, it is said morally: Do not cast me away from your face. He faithfully fears to be deprived of the grace he has received; therefore, he says elsewhere: My eyes are always looking to the Lord (Psalm 24:15). And in the following: Behold, as the eyes of servants look to the hands of their masters, and as the eyes of a maid look to the hands of her mistress, so our eyes are fixed on the Lord our God, until he has mercy on us (Psalm 123:2). Indeed, this is the guiding and principled Spirit who rules the mind, strengthens the affection, draws it to where he wants, and directs it to the higher life.
There are also those who receive the spirit of man, which is in him. Therefore the Apostle says: For who knows the things of a man, but the spirit which is in him (I Cor. II, 11)? He who can know all things, whom the hidden things of man do not deceive, can have dominion over man.