Via How Appealing, Justice Breyer spoke at Yale Law School and, as reported here, identified the five core values of the Constitution as: "democracy, human rights, equality, separation of powers and the rule of law."
So what's missing here?
What about: Federalism.
Quite simply, without the Constitution's commitment to federalism there would have been no Constitution. The drafters -- not all of whom shared this value -- recognized that their document would not be ratified if, in the words of nationalist Gouverneur Morris, it contained anything "too terrible to the states." Thus the drafters, to allay fears of the new national government they were creating, developed the idea of enumerated powers: the national government need not be feared as a threat to liberty because it would have only a few specified powers, with the rest left to the states. This structural protection of liberty became a centerpiece of the federalists' defense of the Constitution during the ratification debates, neatly summed in Madison's observation in Federalist 45 that the "powers delegated ... to the federal government are few and defined."
Even so, the Constitution was almost defeated. It needed nine states to ratify; the first seven came easily. Of the remaining six, North Carolina and Rhode Island rejected it, and in Massachusetts, Virginia and New York substantial anti-federalist sentiment existed, arising in significant part from fear of a powerful national government. Massachusetts was the first of these to vote, in a convention that probably had an anti-federalist majority at the outset. But a deal between moderate anti-federalist Sam Adams and the careful fence-sitter Governor John Hancock allowed a vote for ratification coupled with a call for future amendments -- among them, at Adams' insistence, the predecessor of the Tenth Amendment, reaffirming the enumerated powers structure. Similarly, in Virginia and New York, the Constitution's supporters overcame anti-federalist sentiment in significant part by reassurances that the national government had only limited powers, with most powers reserved to the states. Even so, the vote in all three states was close. Had the Constitution's defenders not been able to point to the enumerated powers structure (and a promise to reinforce it through what became the Tenth Amendment) likely the whole enterprise would have been lost.
Without exaggeration, one might say that federalism is the first value of the Constitution. Justice Breyer may not like it (as we know from his votes), but that's no ground to omit it.