They were once passionate in wanting to steer their country onto a path of liberalisation, rule of law and democracy. And they believed they were making a difference.
But when tanks rolled into Beijing and troops opened fire to crush the pro-democracy movement in Tiananmen Square in the early hours of June 4, 1989, everything changed.
As party conservatives triumphed over reformists in the political struggle, allies of ousted party chief Zhao Ziyang and liberal intellectuals in government think tanks became targets of suppression, as did talented, but outspoken, young intellectuals.
Placed on the most wanted list, some were sent to jail while others fled the country. Some were investigated by the authorities, expelled from state jobs or pressured to leave.
Twenty-four years on, these liberal-leaning people - once the country's intellectual elite - say they continue to be rejected by the government and remain frustrated that they can no longer contribute towards their country.
Most who fled abroad are barred from entering China, while those who stayed can only live on the margins of society.
Most are barred from working in the government and universities, publishing their works and airing their views publicly. Their movements are often monitored by the government.
Bao Tong , the top aide to Zhao and the architect of his economic and political reforms, would have been a leading candidate for entering the powerful Politburo were it not for the crackdown, political analysts say.
But the former director of the party's Political Reform Office spent the rest of his life in jail and under house arrest.
He was sentenced to seven years in prison for "leaking state secrets" and "inciting counter-revolutionary propaganda"- charges he said were fabricated. He remains under house arrest.
Bao, 81, said he had "no regrets" over his personal fate, but he thought it was the country's loss that there was no room for liberal-leaning intellectuals to contribute to the country.
"Many young people had ideals and ambition and were given the chance to express their opinions then," Bao said.
"But now it's very difficult to air new and good ideas … there's only praise or condemnation and very little rational discussion."
His former subordinate, Chen Yizi , was also on the wanted list in June 1989.
The former director of the China Research Institute for Reform of the Economic Structure, a think-tank under Zhao, was forced to flee Beijing after Zhao was placed under house arrest and Bao was jailed.
He boarded a train and eventually reached Guangdong. He then escaped to Hainan , from where he boarded a boat which smuggled him to Hong Kong. Two days later, he flew to France.
In a book published in Hong Kong last month, Memoirs of Chen Yizi - China's Reform in the 1980s, Chen detailed how he repeatedly urged his friend Deng Pufang , the son of paramount leader Deng Xiaoping , to persuade his father to ease tensions between students and the government by publicly acknowledging that students were patriotic.
Confrontation had escalated sharply after a People's Daily editorial on April 26 labelled the movement "anti-party and anti-socialist upheaval" - signalling it would be harshly dealt with.
On the same day as martial law was announced, Chen's institute and other think tanks issued a statement to denounce the government's military control and begged students to stop their hunger strikes.
They also urged the National People's Congress to use its constitutional powers to intervene.
In an interview with the Post last week, Chen, now 73 and suffering from cancer, said he had tried his utmost to stop the tragedy from happening.
"I was trying to persuade the party leaders the students were patriotic, and was also asking the students to leave the square - I was mediating on both sides, but ended up being accused," he said by phone from the United States, where he now lives.
He became "the top most wanted criminal" because the conservative faction accused him of being "a conduit" between Zhao and the students, he said.
But for the past 24 years, what remained the most poignant thing for Chen was that he could no longer serve his country. "All the thinkers have all been purged … it was a disaster," he said.
Zhang Lifan was a researcher at the prestigious government think tank, the Chinese Academy of Social Sciences, in 1989. He was also one of the intellectuals asked by the government to play a mediating role with students, but was later put under investigation.
For more than a year after the crackdown, he was repeatedly interrogated by the police, who threatened to arrest him.
"They wanted to find out what kind of relationship you had with the [liberal] leaders and what kind of message you were passing onto the students," Zhang said. His promising career at the academy came to an end when he was pressured to leave.
And it was impossible for him to find another job at other universities as they were all state-run. He ended up becoming a businessman to make ends meet.
Zhang, 62, said that life outside his government job had given him new perspectives on his thoughts and the chance to think independently.
"When I was in the government, I hoped to help the country solve its problem by providing it with solutions," Zhang said. "But after witnessing the event with my own eyes, I gained a deeper understanding of the regime.
"Now we know that, to uphold the regime, they can do absolutely anything. People in the regime at last realised what their party was all about, and many of them were disillusioned."
Wu Guoguang , a former editor at People's Daily and a policy adviser and speechwriter to Zhao, was one of them.
As one of the youngest members of the party's Political Reform Office, he helped draft the party's report on reform at the 13th party congress in 1987 while aged only 30.
Wu left Beijing in February 1989 for a fellowship at Harvard University, but after the June 4 crackdown, the authorities raided his flat in Beijing and confiscated many of his research materials and personal letters.
He was dismissed from his government job and dared not return through fear of being detained. He plunged into a state of deep depression.
"All the reform measures that we worked so hard for were all burned down at once," said Wu, now a politics and history professor at the University of Victoria in Canada.
"People who shared the same beliefs as us were either killed on the square or investigated by their work units," he said.
"I didn't know what I was going to do. It was like I had lost my compass."
Wu was once hopeful about the prospect of democratisation in his country.
But he said: "1989 totally changed my life. Before, I had a promising career in the government and we wanted to change the regime from within.
"We thought we could make China a democratic country with constitutional rule within 10 or 15 years. I never thought that, nearly 25 years on, it would be even worse than before."
To this day, Wu feels rejected by his country. He said he tried to find teaching jobs in China but was told his "political problems" would be an obstacle.
His name cannot appear in print in China and the shipment of a book on politics he edited for the publisher Routledge was destroyed by the authorities.
"My heart has died completely - I want to do something for China, but there is no opportunity to do so," he said. "I have given up all hope. China will not embark on the road that I imagined it would."
Once hopeful for their country's future, these former leading thinkers are disappointed with the way things have turned out.
The crackdown brought an abrupt halt to the country's fledgling political reforms. Legislation planned for protecting press freedom was quashed and the consensus reached at the 13th Party Congress to separate the functions of the party and government was abandoned.
Constitutional democracy has become a taboo subject.
Speedy economic development in the next two decades under one-party rule and lack of political reform led to crony capitalism, rampant corruption, social inequality and environmental degradation.
"Nowadays, people have no ideals nor passion. Amid moral degeneration, they only want money," said Chen. "The situation now is directly linked with the crackdown, of course."