''On my arrival at Prague, I perceived I was being followed step by step,'' Jacques Derrida said.
He was right. Three days later, Derrida, France's most renowned philosopher, was in a Czechoslovak jail, charged with drug trafficking.
The Prague government, scared by the events in Poland, is cracking down on intellectual freedom in Czechoslovakia, observers say. The regime plans to snuff out any remaining dissident elements before they can gain public support.
''The drug charges against Derrida were absurd, absolutely ridiculous,'' a French government spokesman said. ''Derrida was arrested as an example to Czechoslovak intellectuals not to meet with foreigners and as an intimidation to foreign intellectuals.''
Exiled Czechoslovak leaders agreed with this assessment, but saw even more ominous meaning behind the arrest. ''Poland has scared them,'' said Artur London , leader of the Committee for Defense of Liberties in Czechoslovakia.
''The Czech government is just preparing the psychological climate for a great crackdown which I think will come in a month or two.''
And though French government officials had no information about a new crackdown, the spokesman said, ''Of course, Czechoslovak authorities are vigilant to what happened in Poland and more suppression is not impossible.''
Although an estimated 100 intellectuals remain in prison throughout Czechoslovakia for political offenses, Mr. Derrida was back teaching at the Ecole Normale Superieure here on the evening of Jan 7.
The philosopher, also a professor at Yale University and author of numerous books on symbolism and linguistics, spent only three days in jail before pressure from the French government forced his release.
But instead of lecturing on Descartes as planned his first night back, he spent the entire two-hour class describing what had happened. ''Kafkaesque'' was the word he used to summarize his experiences. The famous Czech author would have well understood the ''diabolical scenario'' that was filled not only with tragedy but also with overwhelming black comedy, he said.
Ironically, Mr. Derrida traveled to Prague last week to do research on Kafka as well as to attend unofficial seminars with independent philosphers and students at the home of Ladislav Hejdanek, a spokesman for the Charter 77 human rights movement. Even more ironically, he said he believes ''someone put the drugs in the suitcase'' when he left his hotel to visit Kafka's home.
Last Wednesday when he went to the airport, he said customs officials began meticulously searching his luggage. Inside the suitcase lining, they found four small packets of a brown substance, he said.
Interrogations started at once at the airport. He was questioned for hours not only about the drugs but also his reason for being in Prague, and even his friends and family.
''You have the right to file a complaint against your incarceration,'' the police interrogator told him. He did so immediately, and just as quickly the policeman shot back, ''Your complaint is refused.''
''It was just like all the cliches,'' Derrida said.
He was then taken to a prison at Ruzyne, some 18 miles from Prague, where he was put in a dungeon some 250 yards long and one yard wide, which he said was very dirty.
Two hours later a drunk Gypsy was thrown in with him.
All he could do, he said, was wait and wonder. ''It was terrifying,'' he said. ''I was scared for my life.''
Since Russian tanks rolled into Prague in August 1968, crushing the ''springtime'' of liberalization, the Czechoslovak government has been harsh with dissidents.
In 1977 more than 300 Czechoslovaks, many of them prominent intellectuals, signed Charter 77, a petition calling on the regime to live up to the pledges it made when it signed the Helsinki Agreement on human rights.
While seeking to assure the regime that it had no political goals by stressing that they were not ''an organization,'' the Chartists insisted that the government recognize freedom of speech, of meeting, and of public discussion.
The government responded by cracking down harshly against dissidents. Exile groups estimate that only about 30 Chartists are currently imprisoned. ''But that's not the only way of intimidating people,'' explained Jacob Francis of the Committee for the Defense of Liberties in Czechoslovakia.
''They are followed everywhere, many stopped every other day or so and brought down to police headquarters to be interrogated. Their wives and children are also stopped, and all of them are denied access to jobs and apartments.''
''Fear is widespread,'' the exiled Mr. London added. ''Remember the tanks from '68 are also still there.''
As a result, although Jacques Derrida looked visibly shaken after his experience, he said he will return to Czechoslovakia because he cannot ignore his oppressed colleagues.
''The reality -- all those prisoners -- remains there,'' he said. ''Until one is touched by something like this, one cannot imagine what a paradise of liberty we live in.''