Today we might reasonably define a spice as the (usually) dried part of a plant used to season or flavour food, typically seeds, fruits, berries, roots, rhizomes, bark, flowers or buds, as opposed to the green leaves and stems. They are often, but not always, strongly aromatic. This is quite a good working definition, but it fails to include substances that have been referred to as spices in earlier times.
The earliest use of spices was for medicines, which then in many cases gradually evolved to culinary use. Black pepper is the best-known example, which became immensely popular for seasoning food from the start of Imperial Rome. Sugar had been used in the kitchen by Europeans since medieval times but only became commonplace in the sixteenth and seventeenth centuries; prior to that it was an exotic luxury spice.
The aromatic resins of certain trees from the Middle East have been used as perfumes and as incense since the Bronze Age, and were also regarded as spices. In medieval times, not only did food have to be seasoned, but it also had to look the part, and in many cases this meant adding colour. Yellow was provided by saffron, egg yolk and later turmeric. Alkanet, the roots of a herb in the borage family, was used to add red, as was Red Sanders – an Indian tree that provided a red dye. Pink could come from rose petals and green from a variety of herbs. Turnesole, a plant of the spurge family, was used for purple or blue. (Even black and white were catered for: black by boiling or frying blood, and white from egg whites, crushed almonds and milk.) There was even a peculiar category of spices from animals; musk (from the caudal gland of the musk deer) and ambergris (from the digestive system of the sperm whale) were used both as perfumes and food flavourings.
Notwithstanding medicinal use, the common thing about all of these substances is that they were unassumed luxuries – and they had great value. The search for them was to change the world.
Extracted from The History and Natural History of Spices by Ian Anderson