In the Formalities lecture series Robin Evans reviews aspects of composition with a view to finding out why those aspects are so often regarded as fundamental categories, and with a view also to showing how they interact with other kinds of phenomena. As with abstraction, fragmentation and ambiguity are key characteristics of 20th century art. Primarily focusing on Cubism, Evans explores the continuities and discontinuities between these two terms. Cubism utilizes fragmentation and ambiguity to represent a picture of the manner of perception itself, incorporating mobility and memory. The resultant breaking apart of the surface of things is also a product of orthographic projection: Georges Braque noted that architectural plans and elevations were more constitutive of reality than perspectival representation. Evans sees elements of such fragmentation and ambiguity as already present in the garden and landscape composition of the late-18th century picturesque of Humphrey Repton and others. NB: Some loss of sound when Robin Evans strays too far from the microphone.