We all use and consume gum Arabic every day. It is irreplaceable in soft drinks. It is a key ingredient in inks and paints, it sticks the coating on glossy magazines and the chocolate pastilles that melt in your mouth but not in your hand. It is used in cosmetics and gel capsules, in lithography, and to form chunks of cat food and fertilizer. It is a component of matches and explosives. It is added to milk to make it creamy, to vegetarian meat to make it tender, to wine to make it clear, and to beer to make it foam. It helps make jams and creamcheese thick and chocolate high in fibre but low in calories. It is even found in toothpaste and in the glue used for dentures. It turns up in stock cubes, instant-dessert powders, laxatives, tobacco, icing and ice-cream, sweets and insecticides.

And gum Arabic turns up rather a lot in history. Some of the most significant events in history – the development of cursive script, the industrial revolution, the insights of Adam Smith, the moment when the first African representative (from Senegal) was delegated to the French Assemblee legislative – would have turned out quite differently without the role played by gum Arabic.

For me gum Arabic does even more. It has lured me to the places where I most like to be, from Mauritania to Sudan, from the shade of boukarous in the Sahel to dimly lit archives in cities from London to Dakar. The more I have asked about it, the more fascinating it has become. The closer I got to its source, the more I found that it is hidden, both by people and by nature.

The tears of two species of acacia have been called gum Arabic since the middle ages, even in the Arab world, where samgh arabi was used as an ingredient in ink and hair pomade, among other things. The acacias that exude gum Arabic do not grow on Arabian soil, but it was in Arabian ports that European crusaders and merchants bought it, and brought it to Italy and France. Ever since, gum Arabic has reflected our view of the Arab world, its second fascinating aspect.