Genesis 2:10

Now is manifested the reason of the truth why the fourth day is called the Tetras, why we fast even to the ninth hour, or even to the evening, or why there should be a passing over even to the next day. Therefore this world of ours is composed of four elements-fire, water, heaven, earth. These four elements, therefore, form the quaternion of times or seasons. The sun, also, and the moon constitute throughout the space of the year four seasons-of spring, summer, autumn, winter; and these seasons make a quaternion. And to proceed further still from that principle, lo, there are four living creatures before God's throne, four Gospels, four rivers flowing in paradise; four generations of people from Adam to Noah, from Noah to Abraham, from Abraham to Moses, from Moses to Christ the Lord, the Son of God; and four living creatures, viz., a man, a calf, a lion, an eagle; and four rivers, the Pison, the Gihon. the Tigris, and the Euphrates. The man Christ Jesus, the originator of these things whereof we have above spoken, was taken prisoner by wicked hands, by a quaternion of soldiers. Therefore on account of His captivity by a quaternion, on account of the majesty of His works,-that the seasons also, wholesome to humanity, joyful for the harvests, tranquil for the tempests, may roll on,-therefore we make the fourth day a station or a supernumerary fast.

After having spoken of Paradise and the day on which it was planted, as well as the introduction into it of Adam, and the Tree of Life and its companion, Scripture turns to describe the river which goes out from its midst, and how it …

The Church, setting forth the likeness of paradise, includes within her walls fruit-bearing trees, whereof that which does not bring forth good fruit is cut off and is cast into the fire. These trees she waters with four rivers, that is, with the four Gospels, wherewith, by a celestial inundation, she bestows the grace of saving baptism. Can any one water from the Church's fountains who is not within the Church? Can one impart those wholesome and saving draughts of paradise to any one if he is perverted, and of himself condemned, and banished outside the fountains of paradise, and has dried up and failed with the dryness of an eternal thirst?

Perhaps, however, those people who like to talk from their own wisdom do not concede again that these rivers are rivers or these waters really waters but propound some different interpretation to people ready to lend them their ears. Let us, however, I beg you, not be convinced by them but block our ears against them; let us instead place our credence in sacred Scripture and heed what is told us there.

Awful in truth are the Mysteries of the Church, awful in truth is the Altar. A fountain went up out of Paradise sending forth material rivers, from this table springeth up a fountain which sendeth forth rivers spiritual. By the side of this fountain are planted not fruitless willows, but trees reaching even to heaven, bearing fruit ever timely and undecaying. If any be scorched with heat, let him come to the side of this fountain and cool his burning. For it quencheth drought, and comforteth all things that are burnt up, not by the sun, but by the fiery darts. For it hath its beginning from above, and its source is there, whence also its water floweth. Many are the streams of that fountain which the Comforter sendeth forth, and the Son is the Mediator, not holding mattock to clear the way, but opening our minds. This fountain is a fountain of light, spouting forth rays of truth.