AS Byatt (2007)

Noel introduced himself to me in the canteen at University College London, when I was teaching there in the 1970s and he was at the Slade. By the end of that lunch we had embarked on a conversation about the construction of works of art, and I had been asked to sit at the Slade table in the bar, and talk to the artists. It was good to talk about making things, and not about criticising them. And Noel talked with extraordinary clarity - and complexity - about making works of art.

I used to walk round the Slade graduate exhibitions with him. He always stood back and let me look and think. Then we would talk about what the work in front of us was doing - it was the range of his interests and intelligence that was impressive. If asked straight out whether he thought something was good, he would give a judgment - but the understanding always came first. He taught me a lot about looking.

The ideas behind his own work were intricate and uncompromising. He said (as Patrick Heron also said of himself) that he was a materialist, and his work was about the pigments he used and the solid form of the canvas or linen he worked on. He painted in grids and webs of ribbons of interwoven colours - the sweep of both his arms was as material as the surface he worked on, and the cuts and stitches he sometimes used. He was interested in removing the illusion of depth from the painted form on the canvas; his work was about itself, its inevitable edges, its thinness as a skin of paint. It was resolutely handmade. It made shimmering fields of lights interacting with itself - a field densely gold, white, scarlet and blue, like an angel, a field darkly green and brown and indigo like the surface of a field.

He wrote wonderfully about surfaces, which he said did not really exist except in the case of liquids - "we would say that a piece of wood has a surface, and a lawn, but perhaps not a field of corn or a forest". The surfaces of his work are about light itself. Including light on corn and forests. His work has been compared with calligraphy or jewellery.

He talked most about the windows of Chartres cathedral - the blue light in and on the surface. He talked about the illumination in the Lindisfarne Gospel, another way of weaving light. He talked about Rembrandt's marks and Titian's gravitational fields. He talked a great deal about Monet, and his rendering of the way light lit things, and then changed, and then changed.

I went with him to see the exhibition of Monet's serial paintings - the changing corn stooks, the change of light and shadow on the surfaces of the facade of Rouen Cathedral, and he made me notice things I might never have seen. He thought endlessly about the relations of paint and light. He was a splendid friend, and a wonderful painter.

· Noel Armstrong Forster, painter and teacher, born June 15 1932; died December 7 2007