He was also a lot more racist than is ever taught in our schools (though not out of line with other whites at the time). Still, he's an interesting study in how a politician's views might evolve over the years, assuming they have the braincells. He went from containment of slavery and a full-throated endorsement of early eugenics and race separatism in 1858, to abolition in 1863, to (paraphrasing) "we should enfranchise the educated and veteran blacks" in April 1865 about 3 days before Booth shot him.
Today we'd cynically call him a triangulating Clintonista, sticking his finger in the air to test the political winds before making a statement.