HISTORY should always turn out like this.The quick end to the coup in Moscow dramatically changes the political and social dynamic in the Soviet Union - for the better. Like a summer downpour, the coup's thunder and lightning has cleared the air. The West can breath a brief sigh of relief. Dogged forces of democracy in the Soviet Union get a giant boost. Disaster has been averted. The coup makes clear that power and authority in the Soviet Union are devolving to the republics (notably the Ukraine and Russia) and their elective bodies. The Soviet center is in eclipse. Boris Yeltsin, who has been on the phone with George Bush and John Major, is rising; Mikhail Gorbachev may be less powerful. Political and democratic reforms had always been ahead of economic reforms in the Soviet Union. Always lurking in the background were the dark, hard-line forces left as Joseph Stalin's legacy. In the past year the hard-liners succeeded in paralyzing Gorbachev and his reform ideas. But the hard-liners misjudged. The leaders of the old Soviet empire thought they could complete a 1964-style Khrushchev putsch. But the two-day coup proved how much has changed. The hard-liners played their hand, and lost. For that reason, now, if ever, is the time for the West to aid the Soviet Union. Aid is an ace card. With hard-liners currently in retreat, aid will show the West's true and best colors: It supports the side of law and democracy. With winter coming and severe food shortages predicted, aid fills a real need and thus supports stability. Aid, moreover, directly appeals to the Soviet people as a form of friendship and solidarity. And if accomplished with enough ingenuity, aid could end up helping not only th e Soviet Union, but the struggling young democracies of Eastern Europe as well. There are many aid routes to take. For example, President Bush and leaders of the European Community and the G-7 nations can speed along the Soviet IMF membership. Modest to substantial direct aid can be given - that will send encouraging signals to the private sector. Why not tie Soviet food aid (Europe has surpluses) to Soviet oil for Eastern Europe this winter? Two caveats: First, aid must not be given until a serious and agreed-on Union Treaty is signed, giving new powers to the Soviet republics. Then, in keeping with the post-coup power structure, it must be distributed through a committee made up of representatives from the republics. Second, the aid must be monitored closely through this committee. The black holes of corruption in the Soviet Union are still too large and numerous.