Agnes Martin often speaks of joy; she sees it as the desired condition of all life. Who would disagree with her?... No-one who has seriously spent time before an Agnes Martin, letting its peace communicate itself, receiving its inexplicable and ineffable happiness, has ever been disappointed. The work awes, not just with its delicacy, but with its vigor, and this power and visual interest is something that has to be experienced.

Sister Wendy Beckett, in her book American Masterpieces, about American painter Agnes Martin.