And if concentration wavered. [fact]
For those to whom books played an important recreational role, the radio was initially disorientating in its offer of a prescribed schedule of entertainment. Against the versatility of opening a book in odd moments of leisure, radio output could only be caught at the appointed hour; and if concentration wavered, there was no turning back a few pages to recap.
Andrew Pettegree, Arthur der Weduwen, The Library- A Fragile Hist…, loc. 805