My answer to where the field came from is that we must first find a thing before we can ask where it came from.

Imagine you are walking down a long length of track in an area that is deserted and there is no way to know who may have come before.

Laying on the ground you find $100. This is exactly enough to buy medicine for your sick child.

Religion would say "God did this" and that is sufficient for your inquiry.

I don't know that I would disagree with that, but if it were me, then on the walk home I would be considering all the possible ways that money would have come to me. Ultimately I would arrive at the conclusion that it must have fallen from someone's wallet.
But who's wallet? Maybe a fellow workers?

So then I would head back to the station and ask my fellow workers, "Did anyone lose something today, like a credit card or cash or something". If no one spoke up, I would then consider the possibility that it blew from someone's table maybe miles away.

At some level they are ultimately knowable, but do I have the courage to seek them out? Or do I just accept the answer that God did it? I can't answer that question until I find $100 while walking down a long stretch of abandoned track.