The Function of Form explores the production of singular affects through systems that relate form and content. This is an essential graphic manual on structural systems and their capacity to produce a variety of forms. Extracting their base geometric unit, a wide range of historical projects from the Medieval to the present are used as systems to proliferate different forms. The book distinguishes tessellation from modulation as a type of flexible system for producing complex repetition through diverse parts. The research presented aims to move architectural experiments away from 'mechanistic' notions of systems for re-producing forms, to 'machinic' notions of systems that determine how parts of an architectural problem interrelate and multiply. This open nature of transversal systems leads to new actualized forms and novel affects.