My point was that at one time separate but equal was considered enlightened by a majority of the population. I agree that short societal memory is a curse we have to work around.

The Constitution is not permanent and unchangeable, it is a living document that can and has been amended to suit new or changing needs. That's why they are called Amendments in the first place. It is by design a lot more difficult to change than other laws, and this is a good thing, but the Founders knew they couldn't get everything right for all time.