I spotted the painting while sifting through a rack of shirts. It was behind some shoes, leaning against the wall with its back to me. It was set inside a hand-cut timber frame the size of a shoe box. This and the thickness of the linen, not to mention the way it was hiding, made me curious.

On getting closer and seeing the name of the painter, I felt myself blushing. Chancing upon a thing of value in a charity shop - should I declare this?

Turning the painting around I saw an abstract composition of earthy tones; pieces of string had been stuck down beneath the paint to break up the rectangle into a field of smaller shapes. It gave the impression of a desert or arid plots of farmland viewed from an aeroplane.

I wasn't a big fan of this artist. I'd never read the biographies he had written during the 1960s and 1970s, never lingered before one of his paintings. But I immediately felt the substance of what I was holding. It was a painting that wanted to be held, a painting which had body - its back and sides as intriguing as its front.

Any guilty thoughts were dismissed, firstly on the grounds that I wanted to keep the painting rather than profit from it, and secondly because the foundation I was buying from had recently been mired in financial controversy.

Abandoning my search for summer shirts I took the painting to the woman at the counter. With a no-nonsense expression she took the object I handed her, scrunched her face at the muddy surface and said: 'What am I supposed to charge you for that?'

from Patrick Hartigan, Offcuts, Gazebo Books, Sydney, 2019