This work was written in 1776 and slavery wasn't abolished until 1860s, what does this mean to you?

In the Declaration, what was Jefferson's argument about slavery? Why were certain words in all capital letters?This work was written in 1776 and slavery wasn't abolished until 1860s, what does this mean to you?
Jefferson was known to have MANY slaves. He even fathered children with at least one of them.This work was written in 1776 and slavery wasn't abolished until 1860s, what does this mean to you?
Could you please post the 'work' so that we can see what you are referring to? Thanks!