" He also said the abolition of slavery and absolute monarchy, and the achievement for civil rights, also once looked unlikely but were achieved."
The things that an engaged population can do are quite amazing. Unfortunately, at this point in time, not only is the population very much disengaged, the government and the media are actively promoting division (ie. partisan politics).
While we have achieved great things in the past, unless people are willing to shake off their complacency, such things will be beyond us in the future.