This chapter suggests that the effects of form on practices of association could only exist if they were inherently related to the material properties of form, and already inherent to practices on their way to materialisation – therefore part of our relationship with form. The same material properties that create the effects of form would have to be active in the genesis of form. The historic role of the block system as a means for the intensification and diversification of interactions and for material resilience in emerging urban societies needs further exploration and empirical verification before it can in fact be determined as a quintessential component of the urban. While urban or proto-urban formations without blocks may be found in archaeological record, of more or less scattered arrangements without fully defined systems of access channels around built forms, the block is the most constant element in the stabilisation of spatial formations that came to be defined as 'urban'.