A principle of the Lance affair is how much the country remains burdened by the baggage of the past. Memory drives many of us, especially in the press and the Congress, to see Watergates and Vietnams everywhere.

Showy efforts to take distances from past administrations buy the present administration far more trouble than it needs. The unintended consequence is multifold assault on that not-little thing, the presidency.

Despite all the talk of Caesarism, the presidency is not an imperial office. On the contrary, measured by what is expected, it is a weak office.

The President is the forcus of the hopes and aspirations of the American people. His office bears responsiblity for national prosperity and well-being. It is supposed to shape consumer demand and influence business investment. It is mixed up with housing, health, education, transport and even race relations. It affects the way people eat, live and go to school.

The President is also charged with responsiblity to maintain the security and strength of this country and its allies abroad. That turns out to mean things like reconciling the view of soliders and scientists, getting Israelis to be nice to Arabs, forging better relations between Turks and Greeks, and figuring out safe ways to live with totalitarian regimes committed to promote the coming-apart of this country. Indirectly, at least, the President holds in his hand the lives of all Armericans.

But the power to meet these responsibilities effectively is fragmented and restained by both the Constitution and national custom. The free-enterprise system, not to mention the absolute right of Congress in matters of taxes and the large powers of the Federal Reserve in matters of money supply, give the President less authority over the domestic economy than any other head of government among the developed countries.

What once looked like plenary powers in foreign policy are now much hedged by the Congressional right to appropriate, the Senate's duty to approve treaties, and the instinct of all Americans, and especially the Congress, to "oversee" foreign operations - the more so as foreign governments have easy access to American opinion and American interest.

Finally, the federally bureaucracy is colonized by powerful domestic interests and the Congress. So the President cannot even give orders to the instruments of his office. He has to beg for help or line up interests or appeal to the country at large. He is, as Clark Clifford, the lawyer for Bert Lance who has served so many Presidents, once observed, "the great persuader."

Every President, in these conditions, must develop extra sources of strength. There are good grounds for trying to build trust and rapport with the country at large, legitimate reasons for manipulating symbols and polishing images, big incentives to find congenial persons with whom to work.

These conditions of the presidential system have not been much favored by the corrosive spirit of doubt and skepticism built by the events of the past decade. Many of us in the press - and me not least - have been too caustic and cynical in judging the motives of the President especially, there has been an overenthusiastic disposition to cry "siege mentality," "coverup," "cronyism," "dirty tricks" and "business as usual."

In the Congress, Vietnam and Watergate have shattered the mystique of the responsible leader who supported the President without fanfare or personal advantage. Now the laurels go to those who can stand up to the executive, show how the President and his men have been cheating on the Constitution and overinvolving the country in dubious commitments.

For their part, the President and his men have exaggerated the claims to be different. They have proclaimed moral standards the Archangel Garbriel could not meet. They have fenced out experienced men at great peril precisely because they were experienced. They have acted as though the most difficult and complicated transactions could be handled by goodness and the fear of God. They have believed in instinct too much, and they have been unbuttoned, and even lax, in addressing themselves to serious matters.

The interplay of these tendencies built the Lance affair way out of proportion. The lesson is that all of us must begin a critical rethinking of the recent past. What has happened since 1963 is not the rule in this country. Except given the most compelling evidence to the contrary, the common interest lies in strengthening the President, which means taking events on their own merits, not on the points of old bayonets.