4 ideas
Bacon distinguishes images that act directly on the nervous system from images that first pass through the brain as an illustrated story or explanation. Illustration tells you what something looks like and so leaves the viewer's sensations untouched. A work that registers as sensation, before the mind has read it, delivers the fact of the subject with more force than a faithful likeness could.
Bacon deliberately provokes chance by throwing paint, wiping areas with a rag, or making involuntary marks. He then applies a strict critical judgment to decide which accidents to keep and build on. Chance supplies marks the conscious will could not invent, and the painter's job becomes recognizing which random marks carry more life than a planned one would. The method is a controlled loop: disrupt the image, then select.
Bacon argues that deforming a figure can bring it closer to the truth of the person than accurate rendering can. The distortion bypasses the viewer's habitual, worn-out way of seeing a face. It restores the shock of the person's actual presence, their 'emanation,' which a correct likeness has made invisible through familiarity. Fidelity to appearance and fidelity to fact can pull in opposite directions.
Bacon preferred to paint friends from photographs rather than from sittings. Their physical presence inhibited the liberties he needed to take with their image, and the photograph gave him distance to injure the likeness freely. He treated photographs, film stills, and medical images as triggers that suggest images, not as models to copy. The mediated image becomes useful precisely because it frees the maker from an obligation to the living subject.