Easy Money and Smart Thinking

This morning I was approached by a lady with a clipboard who asked me if I'd take part in a little market research. Normally I say no to this kind of thing, but two factors swayed me this time: the research was taking place in a nearby church hall complex that I was mildly curious to see, and a £5 note was on offer, just for answering a few simple questions.
 The questions were indeed simple (to do with the local water company); I had the pleasure of looking around the attractive late Gothic interior of the church hall complex (1907, by Gordon & Gunton – it's in Pevsner); and I came out with a new fiver in my pocket. I decided to invest my newfound wealth in a small book, if I could find anything suitable in the Waterstone's around the corner.
 Browsing the shelves, I was surprised to discover a large section devoted to 'Smart Thinking'. What could that be? I wondered. On easy chairs nearby, a respectable-looking elderly man and woman who seemed to be friends were chatting in rather carrying voices. The conversation began, in the usual way, with health and symptoms... I examined the 'Smart Thinking' shelves, soon discovering that it was a mix of popular science, trendy ideas (lefty of course) and instant smart aleck books, but with a few classics dotted about, apparently at random – The Prince (fair enough, I suppose), Utopia (smart?), the Communist Manifesto...
 By the time I tuned back in to the carrying conversation from the easy chairs, the subject had changed, rather alarmingly, to Viagra. Both the lady and the gentleman seemed more than happy that the heyday in the blood was tame, and neither fancied the idea of senile sexual athletics. But that was far from the end of the conversation, as it wandered into the field of what these days are called 'relationships'. The lady gave a particularly lurid account of an evening with a man who seemed to think he had bought her favours for the price of a couple of drinks... But I mustn't pass on any more of what was presumably intended to be a private conversation, even if anyone within 20ft could hear every word. I bought a suitably small book – Carlo Rivelli's Seven Brief Lessons on Physics – and went on my way.
 Incidentally, there was no sign of Montaigne (a truly smart thinker) on those Smart Thinking shelves. It's his 486th birthday today.