Bonaventure, on Isa 55:11

“So shall my word be, which shall go forth from my mouth: it shall not return to me void, but it shall do whatsoever I please, and shall prosper in the things for which I sent it.”

“By means of diffusion, as of brightness out of light, of heat out of fire, of a river out of its headspring, of rain out of a full or humid cloud. In the first diffusion, equality is lacking, for brightness is not the same as light. In the second, closeness is lacking, for heat is not close to fire, since it is the principle neither of its form nor of its origin, but is merely an accident. In the third, simultaneity is lacking, for a spring diffuses itself by flowing, and not all at once. In the fourth, fullness is lacking, for not all of the rain is drawn out of a cloud, but only successive drops. Now, join these four conditions to a single diffusion, one of splendor having equality, of heat having closeness and substantiality, of a river or fountain having simultaneity, and of rain having fullness: and in this way, you will have a trace of the eternal generation. Hence, the Son is sometimes compared to brightness: "Being the brightness of His glory," etc.; at other times, to a flame, as in Moses' bush which represented the person of the Son; or again, as a river or spring: "But a spring rose out of the earth. A river rose in Eden." Again, He is sometimes compared to rain: "For just as from the heavens the rain and snow come down and do not return there till they have watered the earth," etc. And, later: "So shall my word be that goes forth from my mouth," that is, from the Father's heart.”

Imported from an open dataset — not yet checked against the printed edition.