The summer soldiers of the Reagan Revolution are going back to their farms. But before they plant the seeds of a bitter harvest, they should recall that it was in a sunless winter at Valley Forge that the victory of the American Revolution was secured. So, too, will it be in the winter of the Reagan Revolution that its blessings will be either secured or allowed to dwindle.

Yes, it was easy in the summer of '81 for conservatives to dream of the imminent elimination of liberalism, root and branch. Each of us traveled the long road from home to Washington that spring, and brought with us our own vision of a conservative Eden. And yes, it's true that unicorns do not yet graze on the Mall, nor do lions lie down with the lamb. But if Washington is not yet as we wish it, it is far better than we found it.

Tax rates are much lower, conservatives are filling the courts, federal programs no longer expand, regulations are abated, moral values are reverently defended, national defense is enhanced, communism is fought, business is respected, inflation is down, jobs are up, patriotism is revived, and, if you ask me, the weather has improved these last seven years.

It is true that as our dreams brushed up against the reality of an entrenched liberal establishment, we experienced uncertainties, errors, accidents, technical difficulties, the unforeseen -- and their effects on decisions, morale and actions. But thus has it been in all great enterprises. Winston Churchill, at the beginning of World War II, warned his nation that "a steady flow of losses must be expected, occasional disasters will occur. . . . We are buffeted by the waves, but the ocean tides flow steady and strong in our favor."

So, too, is it with American conservatism. We have made mistakes, and we will make more. Only the dead no longer err. The only fatal mistake would be to walk away from Ronald Reagan because he fails to do precisely as each of us may wish. Oliver Wendell Holmes observed that "a great man represents a great ganglion in the nerves of society, or to vary the figure, a strategic point in the campaign of history, and part of his greatness consists in his being there." Reagan is the great conservative leader both because of what he has said and done for a quarter of a century and because he is here at this pivotal moment in our history.

I do not mean to suggest that conservatives on the outside should remain silent when the administration appears to be violating the president's long-held principles. All of us, including the president, want to hear from our allies. But advice and criticism should be tempered by the fact that no one over the years has done more for the conservative movement than the man now sitting in the Oval Office.

Regardless of the particular concerns of the new right, old right, social right, fiscal conservatives, supply-siders, evangelicals, libertarians or strong-defense advocates, American conservatism will be judged in history by the success of Reagan. If he completes his term successfully, all branches of the conservative tree will thrive. If the liberals beat him in the last year with the aid and comfort of disheartened conservatives, we will all lose.

And, I would remind the summer soldiers, the disgruntled, the dejected and the defeated, that it is not Reagan who voted for budget-busting pork barrels such as the highway, water and housing bills. It was not Reagan who voted against Robert Bork. It was not Reagan who spoke free trade while voting to protect inefficient industries in his district.

Reagan has been on the political high wire for seven long years. On one end are the liberals and Democrats shaking the wire for all they are worth. On the other end are some of our disgruntled friends doing likewise. Beneath him is not a safety net, but the hard rock of history.

As we enter the last months of this administration, let us remember that whatever disagreement may exist over important policy issues, there is more that unites conservatives than divides us. An "imperfect" Reagan presidency is not the enemy. Rather, it is the resurgent liberalism that hopes to discredit the president and conservatives in 1988 and to put the country back on the path of big government and high taxes at home and appeasement abroad. It is this that conservative energy must mobilize to prevent at all costs.

The writer is assistant to the president for policy development. "No one over the years has done more for the conservative movement than the man now sitting in the Oval Office."