In the end, we all have to make excerpts from the books and documents we read. In the 16th and 17th centuries, scholars tended to read books in an extrapolatory way, selecting passages to be memorised or copied into common-place books. Sometimes they kept their excerpts in the order in which they came across them. More usually, they tried to arrange them under predetermined headings: virtues and vices, perhaps, or branches of knowledge. Properly organised, a good collection of extracts provided a reserve of quotations and aphorisms which could be used to support an argument or adorn a literary composition. As the historian Thomas Fuller remarked, ‘A commonplace book contains many notions in garrison, whence the owner may draw out an army into the field on competent warning.’
The truth is that I have become something of a dinosaur. Nowadays, researchers don’t need to read early printed books laboriously from cover to cover. They have only to type a chosen word into the appropriate database to discover all the references to the topic they are pursuing. I try to console myself with the reflection that they will be less sensitive to the context of what they find and that they will certainly not make the unexpected discoveries which come from serendipity.