you know that was signed in 1864, right? and you do know the constitution was originally put into action in 1776, right? as in america went almost 100 years with slavery being perfectly legal. you talk about the constitution being in place to give citizens rights and freedoms. i can't thing of anything infringing on a person's freedom more than being told you can be legally owned by another person and have to do exactly what they say exactly when they say it.
so, yes, the constitution was written saying slavery is cool. luckily americans realized it wasn't actually cool and infringed a hell of a lot on the freedoms of black people and looked at the constitution again and changed it. not really sure why you brought this up? it seems to support my point perfectly; that the constitution, as it was originally written, was an imperfect document and that it is silly to never want to change or touch as time passes and society changes. this is exactly what Lincoln did, and, i hope, you agree that it was the right thing to do.