What if someone tried to prevent you from reaching tomorrow...
...and the only way you could move forward was to kill him in the past?
Check out this never-reprinted tale from Ziff-Davis' one-shot Weird Adventures #10 (1951) for the answer!
What's the moral?
You can change history, even if you don't intend to?
Being good, even if it may be to your personal detriment, will be rewarded in the end?
Ah, well, I guess there are some things we're not meant to understand...
It may be just as well that both the writer and artist are unknown.