The White House's budget covers hundreds of federal agencies and $3 trillion in spending, so there is plenty in there to like and dislike.

Most budget commentary criticizes or praises this cut or that hike, or defends or assails this agency or that program. This sort of Beltway budget banter is all well and good, even though the details are likely to change dramatically before a budget resolution is passed.

But President Trump's blueprint tells a more important story to the close reader. The bigger question isn't what agency needs how much money. It's not even about efficiency.

The bigger question is this: Which activities are properly performed by the federal government, and which activities are properly left to other bodies, such as states, local governments, the private sector or nonprofit organizations?

For much of the Washington news media, cutting federal funding for something is the same as opposing that thing. Trump's budget, however, makes a distinction that these critics miss. Federal funding should be for things that are best done by the federal government. Many things are better done at a level of government closer to the individual, or even outside government altogether.

"Subsidiarity" is the word Catholics use to describe the principle that different functions are properly assigned to different levels of government or civil society. This idea runs subtly through Trump's blueprint.

Within the Education Department, for instance, the budget blueprint, "Eliminates or reduces over 20 categorical programs that do not address national needs, duplicate other programs, or are more appropriately supported with State, local, or private funds." In general, "The Department would refocus its mission on supporting States and school districts in their efforts to provide high-quality education to all our students."

At the Energy Department's Office of Energy Efficiency and Renewable Energy, Trump's blueprint doesn't eliminate renewable energy funding, but instead "focuses" it "on limited, early-stage applied energy research and development activities where the Federal role is stronger." In other words, research that can be commercialized is properly carried out and funded by commercial enterprises, not by governments. Obama's EERE, by contrast, became a venture capital fund, picking companies, such as Solyndra, to invest in.

Trump's blueprint has the same prescription for Department of Energy's Fossil Energy Research and Development program and Office of Nuclear Energy, that these programs should fund basic research only.

Also, within DOE, "the Budget eliminates the Weatherization Assistance Program and the State Energy Program to reduce Federal intervention in State-level energy policy and implementation." To liberal Washington Post writer Philip Bump, for example, this means no more insulation. In his fictional account of life under this budget blueprint, America is cold because the federal government is leaving state weatherization programs to their own devices.

The Federal Emergency Management Agency will be a bit tighter with its cash, requiring a 25 percent match from state or local governments for some programs. "The activities and acquisitions funded through these grant programs are primarily State and local functions," the budget document explains.

Budget chief Mick Mulvaney on Thursday defended foreign aid cuts by saying "diplomacy" is a "core function of the State Department" but climate change programs are not, so the latter face the ax.

Why cut the budget of National Institutes of Health? "We think there's been mission creep. We think they do things that are outside their core functions."

Total funding levels matter. Efficiency and demonstration of results are important. But the most important thing in this budget is the White House's efforts to get the federal government back in the business of doing what it should be doing and can do better than anyone else, and leaving the other things, however crucial they are, to the people who can do them better.