One and the same rain comes down on all the world, yet it becomes white in the lily, red in the rose, purple in the violets and hyacinths, different and many-colored in manifold species. Thus it is one in the palm tree and another in the vine, and all in all things, though it is uniform and does not vary in itself. For the rain does not change, coming down now as one thing and now as another, but it adapts itself to the thing receiving it and becomes what is suitable to each. Similarly the Holy Spirit, being One and of one nature and indivisible, imparts to each one His grace “according as He wills.” The dry tree when watered brings forth shoots. So too does the soul in sin, once made worthy through repentance of the grace of the Holy Spirit, flower into justice. Though the Spirit is one in nature, yet by the will of God and in the name of the Son, He brings about many virtuous effects. For He employs the tongue of one for wisdom, illumines the soul of another by prophecy, to another He grants the power of driving out devils, to another the gift of interpreting the sacred Scriptures. He strengthens the self-control of one while teaching another the nature of alms-giving, and still another to fast and humble himself. He acts differently in different persons, though He Himself is not diverse.
St. Cyril of Jerusalem,
Catechetical Lectures 14.12