Wherefore a man can know nothing by himself, save after a natural manner, which is only that which he attains by means of the senses. For this cause he must have the phantasms and the forms of objects present in themselves and in their likenesses; otherwise it cannot be, for, as philosophers say: Ab objecto et potentia paritur notitia. That is: From the object that is present and from the faculty, knowledge is born in the soul. Wherefore, if one should speak to a man of things which he has never been able to understand, and whose likeness he has never seen, he would have no more illumination from them whatever than if naught had been said of them to him.
If you purify your soul of attachment to and desire for things, you will understand them spiritually. If you deny your appetite for them, you will enjoy their truth, understanding what is certain in them.
The soul that is attached to anything however much good there may be in it, will not arrive at the liberty of divine union. For whether it be a strong wire rope or a slender and delicate thread that holds the bird, it matters not, if it really holds it fast; for, until the cord be broken the bird cannot fly.