More copious than this (sea) are (his) streams; purer and deeper; so that one would not err in calling Paul's heart both a sea and a heaven, the one for purity, the other for depth. He is a sea, having for its voyagers not those who sail from city to city, but those from earth to heaven: if any man sail in this sea, he will have a prosperous voyage. On this sea, not winds, but instead of winds the Holy and Divine Spirit wafts the souls which sail thereon: no waves are here, no rock, no monsters: all is calm.
It is a sea which is more calm and secure than a haven, having no bitter brine, but a pure fountain both sweeter than * *, and brighter and more transparent than the sun: a sea it is, not having precious stones, nor purple dye as ours, but treasures far better than those. He who wishes to descend into this sea, needs not various, needs not oil, but much loving-kindness (φιλανθρωπίας): he will find in it all the good things that are in the kingdom of Heaven. He will even be able to become a king, and to take the whole world into his possession, and to be in the greatest honor; he who sails on this sea will never undergo shipwreck, but will know all things well.
But as those who are inexpert in this (our visible sea) are suffocated (in attempting to dive therein), so is it in that other sea: which is just the case with the heretics, when they attempt things above their strength. It behooves therefore to know the depth, or else not to venture. If we are to sail on this sea, let us come well-girded. “I could not,” he says, “speak unto you as unto spiritual, but as unto carnal.” Let no one who is without endurance sail on this sea. Let us provide for ourselves ships, that is, zeal, earnestness, prayers, that we may pass over the sea in quiet.
For indeed this is the living water. Like as if one should get a mouth of fire, such a mouth does that man get who knows Paul well: like as if one should have a sharp sword, so again does such an one become invincible. And for the understanding of Paul's words there is needed also a pure life. For therefore also he said: “You have become such as have need of milk, seeing you are dull of hearing.” For there is, there is an infirmity of hearing. For as a stomach which is infirm could not take in wholesome food (which it finds) hard of digestion, so a soul which has become tumid and heated, unstrung and relaxed, could not receive the word of the Spirit.
Hear the disciples saying, “This is a hard saying: who can hear it”? But if the soul be strong and healthy, all is most easy, all is light: it becomes more lofty and buoyant: it is more able to soar and lift itself on high. Knowing then these things, let us bring our soul into a healthy state: let us emulate Paul,and imitate that noble, that adamantine soul: that, advancing in the steps of his life, we may be enabled to sail through the sea of this present life, and to come unto the haven wherein are no waves, and attain unto the good things promised to them that love Him, through the grace and mercy of our Lord Jesus Christ, with Whom to the Father and Holy Ghost together be glory, might, honor, now and ever, world without end. Amen.
Source: Homilies on Acts (New Advent)