Sir John Templeton, who died on 8 July at the age of 95, was one of the most modest billionaires you could hope to meet. I interviewed him once, when he was visiting England to talk to Prince Philip — in a small stuffy room at the top of a small stuffy club on Green Park, London, where he was staying because he liked it. He could have bought the Ritz next door without noticing, but that would have been extravagant. He would have thought it wrong. He was prepared to spend billions on his causes, but never a penny more than he thought was needed to get the job done.

The job that needed doing, he thought, was to recognize the spiritual aspects of the world as quite as real, as reliable and as worth studying as anything else that science can examine. He would say that he wanted from his philanthropy “new spiritual information”. This is a belief that some atheists and many religious believers — especially those who see in modern science a conspiracy against revealed truth — find laughable or sinister. If I defend it, I will certainly be accused of an interest in the matter, as I have taken Templeton money twice, once as the first winner of his prize for European religious journalism, and once as one of his journalistic scholars of science and religion for two months. But money is actually the least that anyone invests in the question.

Whether or not you believe that the facts of the world are wholly amoral will shape everything about your life. It doesn't, of course, follow that anyone who believes the world is amoral must themselves feel compelled to amorality. You can perfectly well suppose that humans should be good in an amoral world, and you may even suppose that humans should be religious in such a world. But this will always feel arbitrary, false to the facts, not on the winning side.

Conversely, if you believe, with Templeton, that virtue is rewarded, and that a patient, honest exploration of the Universe will reveal spiritual values, you may not want to subscribe to any organized religion, but you will certainly suppose that goodness is the right and natural condition of our lives and that it is evil that demands an explanation.

That kind of optimism was one of the things the whole world loved about the United States in the 1950s and 1960s, when Templeton was making his fortune on Wall Street ($10,000 invested with his main fund in 1954 would have grown to $2 million when he sold out in 1992, netting him a personal profit of $440 million; by that time his total funds were worth $13 billion).

All of this was earned from nothing. He was born in 1912 in a small town in Tennessee, 100 kilometres from Dayton, where the 'Scopes monkey trial', which tested the law forbidding the teaching of evolution, was held; in later life he would boast that he had known John Scopes after the trial. His father was a lawyer who lost most of his money in the Depression; the family were devout Presbyterians, as Sir John remained throughout his life. From Yale, he won a Rhodes scholarship to the University of Oxford, which seems to have given him a lifelong case of Anglophilia: in 1968 he renounced his American citizenship to become a British subject and moved to the Bahamas. He was knighted in 1987. His first wife, with whom he had three children, died in a bicycling accident in 1951; he remarried in 1958, but outlived his second wife too.

His first notable act of philanthropy was to set up an annual prize for “Progress in Religion” which he stipulated should be bigger than the Nobel prizes, thus proving to vulgar materialists that the spiritual mattered. The first recipient was Mother Teresa of Calcutta, in 1973, to whom he gave $85,000 (the prize is now worth well over $1 million) — not a woman one could accuse of progress in theology but she certainly got things done, and this appealed greatly to Templeton's distinctive combination of pragmatism and energetic optimism. More recent winners have tended to be scientists with an interest in the metaphysical, among them Freeman Dyson and John Polkinghorne.

Templeton was sure that in the moral and spiritual realm there could be facts of the matter, and that science could find them. He didn't believe in a literal heaven or hell, or a Garden of Eden, but he was certain that these stories were records of encounters with aspects of reality that demand explanation. He would open the meetings of his fund with a prayer, not because he wanted God to reward them but because he believed that prayer cleared the mind and led to better decisions, even if he could not know why. He would not have been in the least bit disconcerted by the celebrated Templeton-funded experiment on the effects of intercessory prayer on a large sample of heart patients, which showed only that patients who knew they were being prayed for had slightly worse outcomes.

In 1987, he set up a foundation for research into what he liked to call the really big questions. Now with an endowment of $1.5 billion, it has funded an enormous range of research, from cosmology to the cognitive roots of religious belief, and is credited with founding the field of forgiveness research — the effect forgiveness may have on a subject's physical health and well-being — by careful pump-priming funding. The list of moral qualities that he thought science should be looking at was entirely characteristic of the man: “ethics, love, honesty, generosity, thanksgiving, forgiving, reliability, entrepreneurship, diligence, thrift, joy, future-mindedness, beneficial purpose, creativity, curiosity, humility, and awe.”

This is slightly absurd, but at the same time noble. The world would be better off with more of all these things, and he wanted science, with his money, to study them, because he never for a moment doubted that virtues were as real as quarks. He really deserved the title of philanthropist.