[Sacajaweau]

That is not the quote...It reads more like...if he didn’t do anything, it would bother him....it’s called conscience

[Vigilanteman]

You are also correct. But admitting the existence of a conscience would tend to support those who argue that children are born with an innate nature to do good and thus weaken the argument that children are born with a sinful nature.

Since the prevailing theology of the time (and even our time) is that children are born with a sinful nature, I think it entirely possible that Lincoln was taking the opposite side, but if so, I can't see the preacher arguing that Lincoln's decision to save the piglets was motivated from an evil nature.

The story, I think, is much like the C.S. Lewis conundrum cited in the post.