What was going on when I was born?

It could have been mere coincidence, or perhaps it was inspired by a new moon. Whatever the reason, hundreds of the nation's leading intellectuals, writers and artists abandoned their books, canvases and word processors last night to flock to publication parties in Manhattan. If it couldn't have happened in Peoria, it was rare even for New York City. While it is not unusual to have two or even three receptions the same evening at the height of New York's fall publishing season, which runs from mid-September through December, those in the business could not remember a time when there were as many as eight, as there were last night - a night when even the most determined partygoer would have been hard put to make all the rounds. Conversations and Criticism One book-industry executive described it as ''the most diverse celebration of the creative mind in recent memory.''

One of every three students at City College is on academic probation, according to college officials, a rate believed to be one of the highest in the country. This fall, the college tightened its standards for probation as part of a continuing attempt to regain prestige lost during the open admissions era of the 1970's. As a result, college administrators say, 3,604 of the school's 10,740 undergraduates have received letters informing them that they are on probation. ''This is a fairly aggressive policy,'' said Alan Fiellin, dean of general education and guidance at the college, the oldest and best known of the 17 undergraduate units of the City University. ''We are reaching out early to warn students, and it does not mean that all of them are in danger of being immediately dismissed or even that all of them have bad academic records.''

Because of an editing error, an article yesterday on the Long Commission, which investigated the October 1983 terrorist bombing of Marine headquarters in Lebanon, misidentified the chairman. He was Adm. Robert L. J. Long.

The Government, reporting a moderate rise in consumer prices for September, today announced the size of the first automatic adjustment of the income tax for inflation. With the Consumer Price Index up four-tenths of 1 percent in September, the rise for the last 12 months was 4.2 percent. Consequently, in 1985 income tax exemptions, the standard deduction and tax brackets will all be increased by 4.1 percent - an adjustment called indexing. (The difference of one- tenth percentage point results from a technical requirement in the statutory formula.) The adjustment will mean a reduction in taxes for some people, compared with what they pay for 1984.

In his days on Wall Street, Donald T. Regan, the Treasury Secretary, learned a thing or two about selling new securities. Yesterday he showed he had not lost his touch. An offering of $500 million to $1 billion in new three-year 11-month notes designed especially for foreign buyers attracted almost $4 billion in bids. The new Treasury offering met with considerable skepticism when it was proposed last August, but the size of the bids yesterday should dispel most doubts. Last August, some international banking houses grumbled that the new issue failed to offer foreign investors the financial privacy they took for granted. Other critics argued that, to the contrary, the debt promised too much concealment from tax authorities. For his part, Mr. Regan, who headed Merrill Lynch & Company, the nation's largest securities firm, before he came to Washington, publicly defended the issue as fair to investors and workable for tax collectors.

A chart accompanying the Market Place column in Business Day on Tuesday omitted an explanation about a change in the shares of Continental Illinois. Since Sept. 26, they have represented the refinanced corporation.

The Government's most widely followed gauge of inflation, the Consumer Price Index, rose four-tenths of 1 percent last month, the Labor Department reported today. The rise, a shade less than the August increase of five-tenths of 1 percent, was at an annual rate of 4.3 percent. For the last 12 months, the report said, the increase was 4.2 percent. The figures mark the third consecutive year of lowest inflation that the economy has experienced since the early 1970's. Prices rose 3.8 percent last year and 3.9 percent in 1982.

When Yves Saint Laurent sent the first nine models down the runway at the opening of his spring and summer collection wearing sober jump suits in wool jersey or cotton poplin, he took a quantum leap over the other ready-to-wear designers here. He was actually presenting simple clothes for modern women. He explained later that his motto for the spring and summer season was ''purity,'' and it was a welcome development after a week when accessories often overwhelmed the clothes. In some cases, this was just as well.

The price report, the last before Election Day, marks the third straight year of the lowest inflation since the 1970's. Page D1.

The Chrysler Corporation, still benefiting from not having to pay Federal income taxes, said today that it earned $261.6 million, or $1.88 a share, in the third quarter, up sharply from the $100.2 million, or 72 cents a share, earned in the third quarter of 1983. Without the tax-loss carry-forwards that are the result of the huge losses the company piled up from 1979 through 1981, the company's profit would have been $148.2 million, or $1.19 a share. Analysts said Chrysler's earnings were within the range generally expected. ''I was forecasting $1.10 a share on a fully taxed basis,'' said Ann C. Knight of Paine Webber Inc. ''They must have sold a few more cars with vinyl roofs.''

HIGH POINT, N.C. FOR as long as anyone can remember, the twice-yearly furniture exhibition here has been primarily an American show. In 1984, however, Europeans are vying for a larger part of the market. Attracted by a buoyant American economy and the exchange advantages of an expensive dollar, foreign exhibitors at High Point, though they are only 8 percent of the total, have more than doubled during the last two years, up from 40 in the fall of 1982 to 90 this season. This fall's show for retailers began Oct. 18 and will end Oct. 26.

A leading Roman Catholic bishop issued a statement today that criticized the Government and said it was not sincerely seeking peace and was imposing ''new oppressions.'' The prelate, Bishop Pablo Antonio Vega of Juigalpa, who heads Nicaragua's conference of bishops, said Sandinista ideology ''promotes and institutionalizes violence'' and sought to implant ''systems that the people have not accepted or chosen.'' At a news conference, he said the 16- page statement represented his personal views and did not have the status of a pastoral letter since five of the 10 Nicaraguan bishops were out of the country. An aide to the primate, Archbishop Miguel Obando y Bravo of Managua, who is in Rome, said he had read the statement and supported it.