Our Constitution put into practice the concept of Natural Law as espoused in the Declaration of Independence. It is only in the context of Natural Law that our Declaration and Constitution form a coherent whole. While I do claim to be a classical philosopher, I have read enough what our Framer's read to understand what and why they did what they did.
FWIW, the basic sources of my point of view are:
Levin's "Libery & Tyranny," Budziszewski's "Written on the Heart," and "A Miracle That Changed The World," by Skousen.
Pardon me, that is “do NOT” claim to be a classical philosopher!