The water I shall give him will become in him a fountain of living water, welling up into eternal life. This is a new kind of water, a living, leaping water, welling up for those who are worthy. But why did Christ call the grace of the Spirit water? Because all things are dependent on water; plants and animals have their origin in water. Water comes down from heaven as rain, and although it is always the same in itself, it produces many different effects, one in the palm tree, another in the vine, and so on throughout the whole of creation. It does not come down, now as one thing, now as another, but while remaining essentially the same, it adapts itself to the needs of every creature that receives it.
In the same way the Holy Spirit, whose nature is always the same, simple and indivisible, apportions grace to each man as he wills. Like a dry tree which puts forth shoots when watered, the soul bears the fruit of holiness when repentance has made it worthy of receiving the Holy Spirit. Although the Spirit never changes, the effects of his action, by the will of God and in the name of Christ, are both many and marvellous.
The Spirit makes one man a teacher of divine truth, inspires another to prophesy, gives another the power of casting out devils, enables another to interpret holy Scripture. The Spirit strengthens one man’s self-control, shows another how to help the poor, teaches another to fast and lead a life of asceticism, makes another oblivious to the needs of the body, trains another for martyrdom. His action is different in different people, but the Spirit himself is always the same. In each person, Scripture says, the Spirit reveals his presence in a particular way for the common good.
The Spirit comes gently and makes himself known by his fragrance. He is not felt as a burden, for he is light, very light. Rays of light and knowledge stream before him as he approaches. The Spirit comes with the tenderness of a true friend and protector to save, to heal, to teach, to counsel, to strengthen, to console. The Spirit comes to enlighten the mind first of the one who receives him, and then, through him, the minds of others as well.
As light strikes the eyes of a man who comes out of darkness into the sunshine and enables him to see clearly things he could not discern before, so light floods the soul of the man counted worthy of receiving the Holy Spirit and enables him to see things beyond the range of human vision, things hitherto undreamed of.
-From the Instructions to Catechumens by St Cyril of Jerusalem
選讀耶路撒冷主教聖濟利祿要理書
（聖神的活水）
「我所賜的水，將在他內成為湧流到永生的泉源。」這是一種新水，使人生活且湧流不止，湧流到那當得起的人身上。聖神的恩惠、為什麼被稱為水呢？因為萬物都靠水而生存；水產生植物和生命；水以雨的形狀從天降下；雖然它常常以一種形式降下，卻產生多重的效果：水在棕櫚樹上產生的效果是一種，在葡萄樹上則是另一種，如此它在萬物中產生不同方式的效果。水存上的方式本質上常是一樣。雨降下時並不改變，不是每一次採取不同的形狀。然而它適應那接它的事物的本性，而成為適於它們的形狀。天主聖神也是這樣。他是一位，是單純的一個性體，和不可分的，但是他按他所願意的，分施聖寵給每一個人。就如枯槁的樹木得到水分，便會發芽滋長；同樣，有罪的靈魂，由於作補贖，而適於接受聖神，便會結出義德的果實。雖然聖神是單純的，只有一位，但是由於天主的旨意並因基督之名，就能產生許多的美德。
他用這個人的口舌，使他為智慧服務；他以預言光照那個人靈魂；他把驅魔的能力賜給這一個人；他又把詮釋聖經的聖寵賜給其他的人。他加強這個人的自製能力，他教導那個人有關施捨的事；他教給這個人守齋和克苦，教給那個人輕視肉體的利益，教給另一個捨生致命。他在不同的人身上有不同的行動，他自己卻始終不變，如同聖經所載：「聖神顯示在每個人身上，是為了使罪人得益。」
他接近我們時是溫良的，他的臨在散發芬芳，他的軛是極輕的。光明和知識閃爍發光，正預報他的來臨。他懷著真實保護者的心腸而來，因為他來，是為了拯救、治療、教誨、勸告、堅強、安慰並光照人的心靈：首先是那些接納他者的心靈；然後，藉著他、也使其他人的心靈同樣受益。
一個人先前處於黑暗中，忽然看到太陽，眼睛便得見光明，便看清楚從前所看不見的：同樣，那適於領受聖神的人，心靈得蒙光照，便會以超人的方式洞見他以前所不瞭解的事理。
