Born on April 30th

"It is not knowledge, but the act of learning, not possession but the act of getting there, which grants the greatest enjoyment."

"Life stands before me like an eternal spring with new and brilliant clothes."

"The enchanting charms of this sublime science reveal only to those who have the courage to go deeply into it."

"I have had my results for a long time: but I do not yet know how I am to arrive at them."

"God does arithmetic."

"Mathematicians stand on each other's shoulders."

"You know that I write slowly. This is chiefly because I am never satisfied until I have said as much as possible in a few words, and writing briefly takes far more time than writing at length."

"We must admit with humility that, while number is purely a product of our minds, space has a reality outside our minds, so that we cannot completely prescribe its properties a priori."

"The problem of distinguishing prime numbers from composite numbers and of resolving the latter into their prime factors is known to be one of the most important and useful in arithmetic."

"When I have clarified and exhausted a subject, then I turn away from it, in order to go into darkness again."

"To praise it would amount to praising myself. For the entire content of the work... coincides almost exactly with my own meditations which have occupied my mind for the past thirty or thirty-five years."

"To such idle talk it might further be added: that whenever a certain exclusive occupation is coupled with specific shortcomings, it is likewise almost certainly divorced from certain other shortcomings."

"I mean the word proof not in the sense of the lawyers, who set two half proofs equal to a whole one, but in the sense of a mathematician, where half proof = 0, and it is demanded for proof that every doubt becomes impossible."

"I am coming more and more to the conviction that the necessity of our geometry cannot be demonstrated, at least neither by, nor for, the human intellect."

"Further, the dignity of the science itself seems to require that every possible means be explored for the solution of a problem so elegant and so celebrated."

"It may be true, that men, who are mere mathematicians, have certain specific shortcomings, but that is not the fault of mathematics, for it is equally true of every other exclusive occupation."

"When a philosopher says something that is true then it is trivial. When he says something that is not trivial then it is false."

"It is not knowledge, but the act of learning, not possession but the act of getting there, which grants the greatest enjoyment."

"When you say 'no' and you get on the streets and you do an act of civil disobedience, it changes your psychology."

"Change comes when people are willing to commit acts of peaceful civil disobedience."

"The absolute key issue is: how do you create enough political pressure? It's up to us to create that political will and there are tried and tested techniques for doing that. So we're talking about the need for civil disobedience that escalates into a rebellion and uprising."

"We need a grownup conversation about why our political economy is killing life on Earth."

"Some people see protesting as a bit of a dirty thing, and certainly the idea of getting arrested was not on people's radar."

"You have to keep building. Movements have to move forward."

"We've been at war with nature. Now we need to apologize and clean up."

"I planted trees but the idea that you can offset carbon is nonsense - planting trees is more a way of acknowledging harm and apologising."

"My dad was a miner at South Kirkby colliery. He went on strike but he didn't go to the picket line, he just put his feet up and got in my mum's way."

"I do have a rebellious spirit."

"I always had a desire to see change and be part of it."

"What I would say is that in its first iteration, Extinction Rebellion is really about democracy, by calling in for these new democratic forms for people to have their power. And frankly, in many countries of the world, democracy is in just absolute shambles."