Wherefore, it is supreme ignorance for the soul to think that it will be able to pass to this high estate of union with God if first it void not the desire of all things, natural and supernatural, which may hinder it…

For this reason Our Lord, when showing us this path, said through Saint Luke: “He that renounces not all things that he possesses with his will cannot be My disciple”.

And this is evident; for the doctrine that the Son of God came to teach was contempt for all things, whereby a man might receive as a reward the Spirit of God in himself.

For, as long as the soul rejects not all things, it has no capacity to receive the Spirit of God in pure transformation.

[…] Oh, did spiritual persons but know how much good and what great abundance of spirit they lose through not seeking to raise up their desires above childish things, and how in this simple spiritual food they would find the sweetness of all things, if they desired not to taste those things!

[…]  Thus he that will love some other thing together with God of a certainty makes little account of God, for he weighs in the balance against God that which, as we have said, is at the greatest possible distance from God.

It is well known by experience that, when the will of a man is affectioned to one thing, he prizes it more than any other; although some other thing may be much better, he takes less pleasure in it.

And if he wishes to enjoy both, he is bound to wrong the more important, because he makes an equality between them.

Wherefore, since there is naught that equals God, the soul that loves some other thing together with Him, or clings to it, does Him a grievous wrong.

And if this is so, what would it be doing if it loved anything more than God?

John of the Cross (1542-1591): Ascent of Mount Carmel, 1, 5, 2-5.