Corpus Delecti - The Body Of The Crime - was etymologically intended to represent a victim... In this case, the corpse of a murder victim.

It's essence represents the impossibility of a crime without a victim.
But in modern law, well...

https://en.wikipedia.org/wiki/Corpus_delicti

It is interesting to note that by this standard, theft has the following requirement:
"Larceny: 1) Property is missing 2) because it was stolen."

Meaning that pretty much every copyright and anti piracy law would become unenforceable, since theft and making a copy are decidedly different in this scenario.

The current model is akin to, say, a sculptor spending years chiseling a figure out of marble...
Then I come along and take a picture of it, and blow it up, and hang it on my wall...
And then I am prosecuted for theft of the artist's property.

But it sounds so stupid when put that way... ;)