Why did Abraham Lincoln want to free slaves?

He slept with a black woman and fell in love with her

He did believe that slavery was morally wrong, but there was one big problem: It was sanctioned by the highest law in the land, the Constitution. The nation's founding fathers, who also struggled with how to address slavery, did not explicitly write the word "slavery" in the Constitution, but they did include key clauses protecting the institution, including a fugitive slave clause and the three-fifths clause, which allowed Southern states to count slaves for the purposes of representation in the federal government. In a three-hour speech in Peoria, Illinois, in the fall of 1854, Lincoln presented more clearly than ever his moral, legal and economic opposition to slavery-and then admitted he didn't know exactly what should be done about it within the current political system.