Mr Philip Yeo grabs a piece of paper on his table and starts doodling furiously.

"Life," he proclaims, right hand deftly executing a series of lines and dots, "is a series of points".

How a person's life pans out, he says, depends on who he meets, and when.

If he had not secured a Colombo Plan scholarship - which came with a five-year government bond - after his A levels, he would not have graduated with a degree in industrial engineering from the University of Toronto.

"If I had not been bonded, I would not have gone to Mindef," says Mr Yeo, who held various appointments in the Ministry of Defence between 1970 and 1999.

And he would not have met the likes of the late founding Prime Minister Lee Kuan Yew, deputy prime minister Goh Keng Swee and minister for defence Howe Yoon Chong, three men who had a profound impact on his 50-year career as a civil servant.

"I never considered myself a career officer or a civil servant. If not for the bond, LKY, Dr Goh and Howe Yong Chong, I would have gone (into the private sector)," says Mr Yeo, who turned 70 last month. "I tried many times to leave. I stayed on because of the nature of the work."

If he had left, the Economic Development Board - which he steered in the 1980s from traditional industries to new high-tech clusters such as semiconductors, aerospace and chemicals - might have been a different kettle of fish.

And there would have been no A*Star (Agency for Science, Technology and Research), the agency synonymous with his name, or Bio- polis or Fusionopolis, the hubs which helped to put Singapore at the forefront of biomedical research. Ditto no Jurong Island, the petrochemical complex, or Batam the industrial park.

"A lot of things," he says, finishing his drawing with a dramatic dot, "would not have happened".

Indeed, Mr Yeo has left quite a mark on Singapore.

One of the country's most colourful, accomplished and controversial bureaucrats, his life has just been chronicled in a book, Neither Civil Nor Servant, written by Peh Shing Huei, a former China bureau chief and news editor of The Straits Times.

Published by Straits Times Press, the volume details a career which is as long as it is diverse, and achievements which are nonpareil in the Singapore civil service.

Holding court in his cavernous office-cum-library at Economic Development Innovations Singapore (EDIS) - the international development company he set up in 2013 - in Fusionopolis, Mr Yeo is wearing a blue shirt, black slacks and a pair of black Nike sneakers.

The choice of footwear is fitting for a septuagenarian on steroids, one who moves as fast as he talks, a Type A personality so full of beans and ideas that if he were a character in a comic strip, he would have too many thought balloons over his head.

Indeed, holding down a conversation with him is a challenge. In the course of conversation lasting more than two hours, he lunges from topics as diverse as electric cars and American politics to stem cells and Battlestar Galactica.

Many adjectives have been used to describe Mr Yeo: visionary, egotistic, trendsetting, maverick, megalomaniac, arrogant, fatherly... They do not bother him.

"Every time I do a job, I focus on the job. I don't look at the personal implications," he says.

"I don't care what people say. Why should I care? People ask me, 'What do people think of you?' Who cares? It's not my problem."

His self-starting instincts kicked in early.

His father - who worked with the Red Cross - died when he was a toddler. The second of three children, he followed his late mother who worked as a live-in domestic helper while his siblings were raised by their grandmother.

He knew his ticket out of poverty and to an overseas education was a scholarship, so he made sure he got good grades in school.

Since there were no scholarships then for aeronautical engineering - his first choice - he opted to read mechanical engineering at the University of Toronto in 1966. But true to his propensity to "do my own thing", he switched to industrial engineering in his second year.

"When I changed, the PSC (Public Service Commission) didn't know what was going on. The PSC were all run by clerks then," he says with a chortle.

Upon his return in 1970, he agitated for an engineering position after a short spell doing government budgets in the Ministry of Finance.

Serendipity smiled on the brash young man; he was made branch head of the logistics division in Mindef. His job? Come up with systems to equip, feed and clothe the armed forces Singapore was building in the light of the country's independence and the withdrawal of British military forces.

It was, he says, the perfect job fit because his degree schooled him in areas ranging from accounting and organisational psychology to business studies and engineering.

"Logistics to me is problem solving, it's about supply and demand and maintenance. Any war, without logistics, is gone. Guy without bullet, no use. Cannon without shell, no use. Soldier without food, die," he says.

He more than made his mark and was famous for bulldozing through if rules stood in the way of a solution.

"I took a lot of risks because I didn't have patience. My rule was simple: What could they do to me? If they fired me, I would have been happier."

That did not happen. In fact, he vaulted up the ranks.

"I was head of branch in 1970, head of department in 1971, director of finance in 1972 doing the whole defence budget," he says.

It helped that he had a mentor and champion in Dr Goh, then the Minister for Defence, who admired his derring-do and ability to get things done.

Mr Yeo remembers going to Dr Goh, requesting to sign cheques for up to a million dollars, something unheard of in the civil service then.

"I was just 26 or 27 then. I told him the guys who suffered the most were the local contractors because we took months to pay them. Dr Goh said, 'What do you want?' I said, 'I want to sign cheques.'"

Those, he says, were heady times for a self-starter and go-getter like him.

"Dr Goh and LKY and their generation, they got people to do the work and they focused on politics. In that era, there was a lot of delegation and the Government was more preoccupied with policies," he says.

"They left it to us," says Mr Yeo, who helped to build his mentor's vision of developing defence-related companies such as Chartered Industries of Singapore (CIS), which would support the military while being commercially viable. As chairman of CIS between 1979 and 1992, Mr Yeo also pushed for these companies - now known as ST Engineering - to diversify.

Asked if he looked up to Dr Goh as a father figure, he laughs and says: "No lah, he was a slave driver."

But he also admits that if not for the late politician and Mr Lee, he would have long left the civil service.

In fact, Mr Lee - whom he refers to as LKY - stopped him from leaving on a couple of occasions.

In 1999, the founding Prime Minister persuaded Mr Yeo not to accept a $28 million offer from Richard Li - son of Hong Kong billionaire Li Ka Shing - to be executive chairman of his Singapore-based fund management vehicle Pacific Century.

The deal included a $10 million sign-on bonus, $10 million as salary for three years and $8 million in shares and options.

"My wife said we could have bought a big house," he says, mock lament in his voice.

"But LKY called me up and said, 'We depend on you.' The old man kacau'd," he says, using the Malay word for "interfere". "He put psychological pressure on me to stay. LKY was very persuasive."

And so he stayed, became chairman of A*Star until 2007 and beavered away at his plan to turn Singapore into a leading centre for biomedical research.

There were detractors but his initiatives have started bearing fruit. Output from Singapore's biomedical science industry leapt from $6.3 billion in 2000 to $21.5 billion in 2014.

"If I didn't stay, there'd be no biomed, none of this. That's why LKY was appreciative. He once told me, 'The trouble with you is only the older generation appreciates you but the younger does not.'"

Ironically in 2007, he had a public squabble with Mr Lee's daughter, neurologist Lee Wei Ling, over his biomedical research directions.

She said that he did not know what was important because he was not a doctor.

"I didn't need to be a doctor. I was doing science. I'm an engineer and I look at things as a public problem," he says.

Saying that he has made peace with her, he adds: "She has a similar character. She's very direct and blunt, she's just principled."

Asked if he has ever felt that he had bitten off more than he could chew, the man credited with creating billions of dollars of investments and hundreds of thousands of jobs for Singapore says: "No, I always find people to help me. I find slaves. It's very important; it's like contractors and subcontractors."

"I subcontract. I delegate and make sure that things are running but I don't leave them totally unsupervised," adds Mr Yeo, who has spotted and groomed numerous talents including former foreign minister George Yeo and current Manpower Minister Lim Swee Say.

Married in 1971, he and his wife Jane have two children: Eugene, 39, is a professor at the University of California, San Diego, while Elaine, 30, is a psychologist.

The hard-nosed commander gives way to indulgent father when he talks about their achievements. One also discerns the same pride in his voice when he talks about his A*Star scholars: He knows exactly who went to Harvard or the University of Illinois, whose husband is German, and how many of them are parents.

"I always invest in young people. I believe they will take over, they are our future."

He may have slipped out of the public eye but he has not slowed down.

Since setting up EDIS, he has been spending a lot of time giving strategic advice to countries such as Azerbaijan, Kazakhstan and Colombia.

He sleeps just five hours a day and spends a lot of time reading. He has a one-terabyte Dropbox which he likens to a "40-ft kelong" filled with reading materials: "science, medicine, ageing, archaeology, immunology, transplantation, robots and drones ..."

It took a long time before he came around to the idea of a biography, one which will no doubt reignite debate about his legacy.

But Mr Richard Sykes, the former head honcho of GlaxoSmithKline and rector of Imperial College, believes Singapore would have been different without his imprint.

In Neither Civil Nor Servant, he describes Mr Yeo as one of the great developers of the country.

"You can have a visionary like Lee Kuan Yew but somebody has to put it into practice. Philip puts things into practice. Philip was a doer and you needed doers, particularly in developing economies."