22 Great indeed, and all-powerful in gifts, and wonderful, is the Holy Ghost. Consider, how many of you are now sitting here, how many souls of us are present. He is working suitably for each, and being present in the midst, beholds the temper of each, beholds also his reasoning and his conscience, and what we say, and think, and believe. Great indeed is what I have now said, and yet is it small. For consider, I pray, with mind enlightened by Him, how many Christians there are in all this diocese, and how many in the whole province of Palestine, and carry forward your mind from this province, to the whole Roman Empire; and after this, consider the whole world; races of Persians, and nations of Indians, Garbs and Sarmatians, Gauls and Spaniards, and Moors, Libyans and Ethiopians, and the rest for whom we have no names; for of many of the nations not even the names have reached us.
Consider, I pray, of each nation, Bishops, Presbyters, Deacons, Solitaries, Virgins, and laity besides; and then behold their great Protector, and the Dispenser of their gifts;— how throughout the world He gives to one chastity, to another perpetual virginity, to another almsgiving, to another voluntary poverty, to another power of repelling hostile spirits. And as the light, with one touch of its radiance sheds brightness on all things, so also the Holy Ghost enlightens those who have eyes; for if any from blindness is not vouchsafed His grace, let him not blame the Spirit, but his own unbelief.
Source: Catechetical Lectures (New Advent)