The core American idea is not the fortress, it’s the frontier. First, we thrived by exploring a physical frontier during the migration west, and now we explore technological, scientific, social and human frontiers. The core American attitude has been looking hopefully to the future, not looking resentfully toward some receding greatness.

The hardship of the frontier calls forth energy, youthfulness and labor, and these have always been the nation’s defining traits. The frontier demands a certain sort of individual, a venturesome, hard-working, disciplined individual who goes off in search of personal transformation. From Jonathan Edwards to Benjamin Franklin, Abraham Lincoln to Frederick Douglass, Americans have always admired those who made themselves anew. They have generally welcomed immigrants who live this script and fortify this dynamism.

The Republican Party was founded as a free labor party. It believed in economic diversity, cultural cohesion and national greatness. The entrepreneurial economic philosophy was highly individualistic, but strong local communities built a web of nurturing relationships and shared biblical morality helped define common standards of character.

This American vision champions social mobility. The original Republicans were not for or against government, they were for government that sparked mobility; they were against government that enervated ambition. These Americans heavily invested in schools at a time when other nations were investing heavily in welfare states. These Americans built railroads and roads to increase mobility. They tore down social, racial and legal barriers to give poor boys and girls an open field and a fair chance.

Today, the main enemy is not aliens; it’s division — between rich and poor, white and black, educated and less educated, right and left. Where there is division there are fences. Mobility is retarded and the frontier is destroyed. Trumpist populists want to widen the divisions and rearrange the fences. They want to turn us into an old, settled and fearful nation.

The Republican Party is supposed to be the party that stokes dynamism by giving everybody the chance to venture out into the frontier of their own choosing — with education reform that encourages lifelong learning, with entitlement reform that spends less on the affluent elderly and more on the enterprising young families, with regulatory reform that breaks monopolies and rules that hamper start-ups, with tax reform that creates a fair playing field, with immigration reform that welcomes the skilled and the hungry.

It may be dormant, but this striving American dream is still lurking in every heart. It’s waiting for somebody who has the guts to say no to tribe, yes to universal nation, no to fences, yes to the frontier, no to closed, and yes to the open future, no to the fear-driven homogeneity of the old continent and yes to the diverse hopefulness of the new one.