Have great concern for these portals the eyes. Most robbers enter through these portals to overthrow the castle of the soul. Had the forefathers guarded their eyes, they would not have been exiled far from God and Paradise. 'The woman saw that the fruit of the tree was good...' (Gn 3:6).
Unless the inner man meditates upon the law of God and is nourished thereby, unless he is strengthened by reading and by prayer, he is conquered by the outer man, and he serves his master.
A man standing on the seashore sees the immense expanse of water, but his eye can embrace only a small part and cannot reach its limit. In the same way, a man who, through contemplation, is given to see the limitless ocean of Divine glory and to see God Himself with the eyes of his mind, sees God and the infinite vastness of His glory, though not the whole as it really is, but only as much as is possible for him.