This is a difficult one to say for sure as it is not a common or modern usage. However I think this is a little more literal. Edge as a verb can mean: to make or force (one's way) gradually by moving sideways. http://www.dictionary.com/browse/edge So little kids might hide behind the sofa when a stranger shows up because they are shy. In many homes, you can find furniture might have a 20cm gap between itself and the wall. I think this assumption is supported by the remainder of the quote.: "For shyness is the protective fluid within which our personalities are able to develop into natural shapes. Without this fluid the character becomes merely standardized or imitative: it is within the tender velvet sheath of shyness that the full flower of idiosyncrasy is nurtured: it is from this sheath alone that it can eventually unfold itself, coloured and undamaged. Let the shy understand, therefore, that their disability is not only an inconvenience, but also a privilege. Let them regard their shyness as a gift rather than as an affliction. Let them consider how intolerable are those of their contemporaries who are not also shy" - http://www.goodreads.com/quotes/239431-let-us-educate-the-younger-generation-to-be-shy-in