Therefore it is proper to divine providence to keep things in being. But artificial things are preserved in being by virtue of natural things, as a house by the solidity of its stones. Therefore natural things are not preserved in being otherwise than through the power of God. The impression made by an agent does not remain in the effect when the action of the agent ceases, unless that impression turns into and becomes part of the nature of the effect. But what belongs to the nature of a superior genus in no way remains after the action of the agent is over, as light does not remain in a transparent medium after the source of light is taken away.
Nothing then can remain in being when the divine activity ceases.
On either theory we must say that things are preserved in being by God. Things therefore are, so long as He wills them to be. His will then is the upholder of creation. On the other hand, if things have emanated from God from all eternity, it is impossible to assign any time or instant in which first they emanated from God. Either then they were never produced by God at all, or their being is continually coming forth from God so long as they exist.