Do you know where the Lincoln quotation comes from? I would be cautious about quoting it out of context. My guess is that it was a nasty remark about blacks. He made a similarly folksy riddle in the Lincoln-Douglas debates:

"Any system of argumentation that... argues me into the idea of perfect social and political equality with the negro, is a species of fantastic arrangement of words by which a man can prove a chestnut horse to be a horse chestnut."

Here's a link to my source.