Possibly as a result of wishing to make what is called reading a more efficient practice, yielding greater clarity and comprehension, Irish monks, and soon the Anglo-Saxon confreres at Sherborne, for example, first put dots between words, and then spaces. Influence from Syriac practice directly from early texts transported to Ireland, there might have been, and ancient Hebrew word-spaced manuscripts clearly influenced these, but still, it was the periphery of Early Medieval culture that became the center for this important innovation. Their missionary activities are well known, but less well known is the diffusion of word spacing that accompanied it. Saenger integrates the most recent findings of modern behavioral psychology on visual, memory, and learning skills. Memory must interact to 'see' a word in x number of letters.
Brains register just about as many letters at a certain eye performance.
It is safe to conclude that human brains have not evolved all that much since 750, so this research can really yield interesting inferences. Saenger has made some of these arguments before, particularly about silent reading, but here he offers a full exploration, and in a sense erudite corroboration for these views. Because reading is a skill so central to so many aspects of culture, Saenger's study of reading has much to say about cultural history in a world history perspective. Saenger's book is a model study of the creation and extension of practice that has long since ceased to be explored in words or teaching. Word spaces are part of the Braudelian routine, like brushing teeth, that is, these are practices that fall consistently below the discursive.