At its edges, a painting makes its surrender to reality. The ways in which it can do so are endlessly revealing, as infinite as the potential forms of painting itself.

Many of Bonnard's later paintings are shot through with a powerful sense of morbidity. The self-portraits he painted after catching sight of himself in the various mirrors in the house - the mirror in the bathroom or the mirror in his bedroom, still lit from above by a single accusatory light bulb - are almost appallingly raw.

The edge of a painting is its frontier... where the artist negotiates his boundaries with the real world... where art begins and ends and where the eye enters and leaves the image. It determines, in an infinitely subtle number of ways, how you read a painting - which, unlike a book or a piece of music, has no pre-determined beginning or end.

The edge in modern painting is charged with neurosis it meets a world that no longer confirms it but which is hostile or at best indifferent.

Ann Winder-Boyle's small-scale encaustic pictures always reward a second look - they have an intriguing edge of darkness about them.