You might look up the meaning of "the laws of nature and of nature's God..."
I believe that beats your claim of "Perpetual", which is a word that isn't even in the US Constitution.
The United Kingdom was a "Perpetual Union" too.
There is no real “meaning” of Natural law; it is a philosophy without a definitive definition. Some of its believers refused to admit slavery was against Natural Law.
The Union was created by the “Articles of Confederation AND Perpetual Union”.
The reason the Constitution was created was to make the Union “more perfect.” And it did.