As the years pass and an artist continues to work and create art, it is often interesting to follow the evolution of what the artist creates. Sometimes an artist is "cursed with success" at an early age and is tempted to continue producing art in the winning formula, without much incentive to try new things and push for growth.

Every great artist shows change and development during his or her career - one only has to remember Vincent Van Gogh or Paul Gauguin, Claude Monet or Pablo Picasso, to name some artists rather at random. It should be axiomatic that artists evolve in their art for as human beings, we all change and develop as the years pass. Nonetheless, some artists are more dramatic in their evolution than others.

I was reminded about these potential huge leaps and changes that artists can make when I was reading about an exhibition running until 20th March at the National Portrait Gallery in London. Entitled Bridget Riley: From Life, it is a selection of the drawings that Riley did as a student at Goldsmiths College, London, in 1949-52. Most people think of Bridget Riley's work as the vibrant, brilliantly coloured, rhythmic compositions that dance and swoop in patterns in almost strobe-like fashion. An exhibition of such paintings, energetic and elegant, is also on view until May 22nd at the National Gallery, London.

Nonetheless, the drawings shown at the Portrait Gallery remind us that she started out very much involved and passionate about drawing from life, as well as closely studying the works of great artists - Raphael, Rembrandt, Ingres, Seurat, etc. - in the print room at the British Museum. Her drawings, such as Older Woman looking down, 1950, underscore the value she places on keen observation. She catches the sense of the body in space, how the head feels as the woman tilts her head reflectively, the resigned expression in the eyes. Riley's drawing practice helped her refine her immaculate sense of structure and taught her that there is a continuity in art's concerns down the ages. Her own drawing and her study of the Old Masters, she explains, "gave me the means to embark on my own work with confidence, and to this day this particular knowledge forms the basis of everything I do in the studio." As Andrew Lambirth also remarks in an article in the 5th February edition of The Spectator, "drawing gave her the necessary exercise in looking and organising information, and the means of bringing eye, hand and mind into fruitful relationship."

It is inspiring to measure the trajectory of such an artist: the serious art student carefully observing her portrait model at Goldsmiths evolves into a richly inventive, energetically wonderful painter, creating memorable abstract art, yet still closely linked to the great painters of the past.