Arguably one of the most useful inventions of the 20th century, the humble paper clip is an excellent example of lateral thinking. When, in 1900 Johann Vaaler, a Norwegian, patented the design, little did he think that since then billions have been made and used.

The are many schools of thought as to who invented it. Some say Herbert Spencer, he who coined the phrase 'survival of the fittest,' others Samuel B. Fay. Whatever, the truth, there's no gainsaying the genius of bending a piece of wire into a shape that keep pieces of paper together. Which is no doubt why in 1989 the Norwegians erected an enormous paper clip near Oslo in Vaaler's honour. Let it be a symbol for the beautiful simplicity of lateral thinking.