BECAUSE THOSE sunny Californians at the White House are not used to changing seasons, it is possible that they are misled by our gorgeous Washington spring. I cannot remember a more exquisite season in our city, longer and more gentle than usual, full of blooming promise. The city is easy to love in springtime.

After spring, Washington comes to summer. When our dedication to good government is tested by hot and muggy reality. A newcomer cannot truly know how he feels about the capital city until he has endured a steamy summer or two.

My metaphor is imperfect, but the point is right. The Reagan presidency, despite its bold and brilliant political strategy, is still at the beginning, still defining itself and discovering flaws and complications in its own grand themes. The president himself, despite his gallantry in the face of personal adversity, is yet to meet the hot weather of political Washington.

Am I too jaded? Too cynical to believe that our new leader will stick by his good intentions and high principles when the going gets rough? I hope not. I hope I am describing, instead, the cyclical realities which no legislature can repeal, which test every leader in good time. This is the human drama that makes Washington endlessly fascinating -- when grand ideas run into real politics -- and we are never quite certain how the play will end.

Ronald Reagan has already blinked a couple of times. He caved awkwardly to the auto industry's pleas for protection from the Japanese. He huffed and puffed at the Russians but retreated before American grain farmers who wish to sell their wheat to the godless Commies. In Washington, where lobbyists and legislators look carefully for the soft spots, and in foreign capitals, where governments makes strategy from scattered tea leaves, the true cynics may already have measured the man and concluded that in the right circumstances, with skillful political pressuring, this guy can be had. In my own perverse way, I find this more reassuring than disappointing.

To make my point about the changing seasons, I want to go back to the original question everyone asked in January: What does the Reagan administration intend to do to Washington? In broad terms, the answer seems rather negative to the permanent residents, since the new resident proposes to hack, shrink and eliminate an impressive list of what is: federal programs, agencies, policies and powers. In popular usage, this agenda is described as: aConservative Republican President Tears Down the House that Liberal Democratic Presidents Built.

But that obscures an important truth about the Reagan program, one which complicates the easy political formulations now in vogue. To an extraordinary degree, Reagan's agenda repeals not only the programs and policies created by old Democratic administrations, but also by old Republican ones. Indeed, much of what Reagan now denounces as useless and wasteful was invented a few years back under the shining eagles of Richard Nixon and Gerald Ford. Yesterday's reforms have become today's scandals, and hardly anyone cares to remember who created these fiascos.

The budget director denounces the Federal Financing Bank as a sort of backdoor window where federal agencies can sneak up to the Treasury and borrow freely, concealing their true spending levels. But the Federal Financing Bank was invented in Richard Nixon's Treasury Department as a way to get control over government borrowing.

Under the banner of free enterprise, the new administration hacks away at Conrail and Amtrak. Both public railroads were created by Republicans.

The new scandal of housing subsidies is "Section 8" rent supplements, the fastest-growing welfare program in the federal galaxy of welfare programs. That scandal started in 1974 when Republicans were cleaning up the mess in housing created by the free-spending Democrats who preceded them.

The list goes on. A couple of friends and I sat down the other day and made a quick, casual list of Republican inventions which are now being denounced by the new Republican government. Professional Standards Review Organizations, the PSROs that were supposed to hold down rising hospital bills, fathered by an HEW secretary named Caspar Weinberger. The Environmental Protection Agency, which took air and water quality away from the industry-dominated Interior Department in the early Nixon years (now, it seems, Reagan wants to give them back to industry).

Federal regulation of bilingual education was invented by the Ford administration, signed by an education commissioner named Terrel H. Bell, who happens to be back in town now as secretary of education, denouncing the fruits of his own earlier labors. The Department of Energy, nee the Federal Energy Administration, and a collection of energy-conservation programs were born in the Nixon government under the tutelage of that old free marketeer, William Simon; Reagan now wants to disassemble them. Speaking of energy, Nixon was the one who started price controls on oil.

There are many other programs that the new folks would like to bury or at least reduce substantially, Revenue sharing. Block grants for community development. CETA. And Social Security indexing. The Reagan team hasn't quite gotten up the nerve yet to attack the Social Security indexing but, when they do, the argument will doubtless be made that indexing was another case of liberal largesse gone haywire, the runaway soup line, to mix David Stockman's favorite metaphors.

But indexing Social Security to the cost of living originated as a "good government" reform, a way to contain the free-spending of biennial increases legislated by Congress for political points. Richard Nixon in his gracious manner took full credit at election time. When the checks went out to the old folks, he sent personal notes to each of them, a month before the 1972 election. I sort of doubt that Ronald Reagan or any other politician will send notes to the elderly, taking credit for the new "reforms" that are coming. s

The point is simple: Ideas that are transmuted into actual government programs, often good ideas, change their nature along the way. The original ideas are battered by political tradeoffs or contradicted by changing realities or exposed as fundamentally wrongheaded. Good ideas and grand theories meet reality. Sometimes in the course of human events, maybe most of the time, reality wins.

Which brings us back to the new president. Personally, I am reassured by the easy manner in which the president sidesteps his own hard-line rhetoric and overheated ideology in favor of pragmatic political decisions. That confirms what longtime students of Reagan, particularly The Post's White House correspondent, Lou Cannon, have always insisted was the core of Reagan's political style. One eye on the teleprompter and the other eye on the voters.

Nevertheless, these presidential actions and others beyond his control begin the season of contradictions and contractions which every president eventually confronts. While the White House was bailing our Detroit and satisfying Midwest farmers, the Federal Home Loan Bank Board was taking care of the savings and loan industry by eliminating mortgages with fixed interest rates. This is another form of indexing against inflation, and yet the Reagan administration hardly raised a murmur against it.

Wall Street, likewise, remains unconverted by the "supply side" sermons and, as long as the bond market is skeptical, the long-term growth which Reagan promises is most unlikely. That means, in turn, that the president will have to do something more to convince them, just as Jimmy Carter and Gerald Ford and Richard Nixon had to do more.

Congress, for now, has bought the budget reductions in Reagan's blueprint, but everyone on Capitol Hill knows that this first victory is only that, that we must now wait to see, at dozens of crucial subordinate levels, whether Congress will stand by the good intentions of the budget resolution or cut and run when the public grasps what is actually being done. For that matter, we will wait to see how firmly the president stands himself, when the heat is upon him.

Summers in Washington are always uncomfortable, but this summer, I think, is going to be as extraordinary as the spring.