19 Now Jesus, seeing that the woman did not understand, and willing her to understand, says to her, “Call your husband.” “For the reason why you know not what I say is, because your understanding is not present: I am speaking after the Spirit, and you are hearing after the flesh. The things which I speak relate neither to the pleasure of the ears, nor to the eyes, nor to the smell, nor to the taste, nor to the touch; by the mind alone are they received, by the understanding alone are they drawn up: that understanding is not with you, how can you apprehend what I am saying? 'Call your husband,' bring your understanding forward.
What is it for you to have a soul? It is not much, for a beast has a soul. Wherein are you better than the beast? In having understanding, which the beast has not.” Then what is “Call your husband”? “Thou dost not apprehend me, you do not understand me: I am speaking to you of the gift of God, and your thought is of the flesh; you wish not to thirst in a carnal sense, I am addressing myself to the spirit: your understanding is absent. 'Call your husband.' Be not as the horse and mule, which have no understanding.”
Therefore, my brethren, to have a soul, and not to have understanding, that is, not to use it, not to live according to it, is a beast's life. For we have somewhat in common with the beasts, that by which we live in the flesh, but it must be ruled by the understanding. For the motions of the soul, which moves after the flesh, and longs to run unrestrainedly loose after carnal delights, are ruled over by the understanding. Which is to be called the husband?— that which rules, or that which is ruled?
Without doubt, when the life is well ordered the understanding rules the soul, for itself belongs to the soul. For the understanding is not something other than the soul, but a thing of the soul: as the eye is not something other than the flesh, but a thing of the flesh. But while the eye is a thing of the flesh, yet it alone enjoys the light; and the other fleshy members may be steeped in light, but they cannot feel the light: the eye alone is both bathed in it, and enjoys it.
Thus in our soul there is a something called the understanding. This something of the soul, which is called understanding and mind, is enlightened by the higher light. Now that higher light, by which the human mind is enlightened, is God; for “that was the true light which enlightens every man coming into this world.” Such a light was Christ, such a light was speaking with the woman: yet she was not present with the understanding, to have it enlightened with that light; not merely to have it shed upon it, but to enjoy it.
Therefore the Lord said, “Call your husband,” as if He were to say, I wish to enlighten, and yet there is not here whom I may enlighten: bring hither the understanding through which you may be taught, by which you may be ruled. Thus, put the soul without the understanding for the woman; and having the understanding as having the husband. But this husband does not rule the wife well, except when he is ruled by a higher. “For the head of the woman is the man, but the head of the man is Christ.” The head of the man was talking with the woman, and the man was not present.
And so the Lord, as if He said, Bring hither your head, that he may receive his head, says, “Call your husband, and come hither;” that is, Be here, be present: for you are as absent, while you understand not the voice of the Truth here present; be present here, but not alone; be here with your husband.
Source: Tractates on the Gospel of John (New Advent)