The answer is that it relates to the thing when it exists, in the sense that it is what makes the thing exist—not that the thing already existed without it and was then made existent by it as well.
He said:
“Such doubts, as you can see, are beyond the power of dialectic to resolve. This, therefore, must not be made a starting point for knowing Allah, Most High, particularly for the general public. The way to knowledge of Allah, Most High, is sounder and clearer than this, as we shall explain later.”
He said:
“As for the second premise, which states that all accidents are originated, it is a doubtful premise. This matter is just as obscure in their case as in the case of bodies.
“We have observed some bodies coming into being, and likewise some accidents. There is therefore no difference between the two in proceeding from the observed to the unobserved. If, in the case of accidents, the judgment concerning those observed must be extended to those unobserved—I mean that