If you love books and live in or around Edinburgh - or beyond - you may be familiar with the Christian Aid Book Sale held annually at St Andrew's and St George's Church, on George Street.
It's always popular because there's a huge range of books available, at very low prices, most between 50p and £2. Buying books online is all very well but there's nothing like browsing actual books and stumbling on something unexpected. The Sale is rather like beachcombing, each year washing up some unusual specimens.
One curio I came across this year was a little collection of essays by a certain Horatio Greenough, a 19th century American sculptor who had some interesting thoughts about design theory. Greenough's significance is indicated in the title of the book, Form and Function. It's so titled because although he didn't coin the term - the actual phrase was first formulated by the architect Louis Sullivan - Greenough's essays, published in the 1850s, offer the first extensive discussion of the concept of inherent form, a good half century before it became a central component of modern design theory.