Freeman Dyson
From the Introduction to The Sun, the Genome, and the Internet

When I was seventeen years old I came as a student to Cambridge University and got to know the famous mathematician Godfrey Hardy.

Almost all the mathematicians and scientists were away, helping to fight the Second World War.  There were no graduate students and very few advanced students of any kind.  All that was left of the mathematical life of Cambridge was the old and famous professors and a handful of very young undergraduates.  Hardy, who was then sixty-four years old, was depressed and miserable.  He was already suffering from the heart ailment that would cripple him a few years later.  He never spoke about the war that was raging around us; he abominated war so deeply that he could not bring himself to speak about it.  He gave lectures on the pure mathematics that he loved to four or five students sitting around a small table in a small seminar room.  In that little room we sat within a couple of feet of Hardy, three times a week for two years.  He lectured like Wanda Landowska playing Bach on the harpsichord: precise and totally lucid, but displaying his passionate pleasure to all who could see beneath the surface.  Each lecture was carefully prepared, like a work of art, with the intellectual denouement appearing as if spontaneously in the last five minutes of the hour.  For me these lectures were an intoxicating joy, and I used fo feel sometimes an impulse to hug that little old man with the white hair two feet away from me, to show him how desperately grateful we were to him for his willingness to go on talking.

A year before I came to Cambridge, Hardy had published a little book with the title A Mathematician’s Apology.  The book was written for readers with no mathematical training, introducing them gently into the world of mathematics in which he was at home.  He was a very pure mathematician, and the message of his book is that pure mathematics is the only kind of mathematics worthy of respect.  He wrote: “A mathematician, like a painter or a poet, is a maker of patterns.  If his patterns are more permanent than theirs, it is because they are made with ideas.”  He was himself as an artist, creating works of abstract beauty.  He saw applied mathematics as second-rate mathematics, more often doing harm than good, and hated applied mathematics with special intensity when it had anything to do with war.  He proudly claimed that he had never done anything in his life that could be considered useful. Everything he did was a work of art and was done with style.  His mathematical papers are beautiful in style as well as in content.  He wrote as clearly and as elegantly as he thought.