As a species, as we progress ethically to more inclusive social norms, those considered the enlightened leaders of their time, like Jefferson can be seen from two contrasting perspectives, the norms of their time and the norms of our times.
As we judge others in the past for failures to recognize unjust social norms prevalent in their time, so too will we be judged by our descendants for social norms they will recognize as unjust, but which we collectively haven’t yet.
How long it takes to shake off the shackles that prevent the recognition of the dignity of each and every human INTERbeing. Each living person of modernity owes his or her existence to all our ancestors, whose social dynamics, for better or worse, shaped the world we inhabit today.
As we evolve, we are engaged in a constant cultural evolutionary process, as we incrementally recognize unjust social norms and attempt to stop their further indulgence, reset our behavior and go towards new, more just ones.