Demand curveIn a demand schedule, a demand curve is a graph depicting the relationship between the price of a certain commodity (the y-axis) and the quantity of that commodity that is demanded at that price (the x-axis). Demand curves can be used either for the price-quantity relationship for an individual consumer (an individual demand curve), or for all consumers in a particular market (a market demand curve). It is generally assumed that demand curves slope down, as shown in the adjacent image.
Sacrifice humainvignette|260px|Enfants de Llullaillaco, Sacrifice humain chez les Incas, Province de Salta (Argentine). Un sacrifice humain est un rite religieux qui a été pratiqué dans la plupart des civilisations, notamment au Néolithique et durant l'Antiquité, le plus souvent pour s'attirer les faveurs des dieux, par exemple pour conjurer la sécheresse, ou pour que les personnages importants tels que les souverains soient accompagnés dans l'au-delà par les sacrifiés.
Animal sacrificeAnimal sacrifice is the ritual killing and offering of one or more animals, usually as part of a religious ritual or to appease or maintain favour with a deity. Animal sacrifices were common throughout Europe and the Ancient Near East until the spread of Christianity in Late Antiquity, and continue in some cultures or religions today. Human sacrifice, where it existed, was always much rarer. All or only part of a sacrificial animal may be offered; some cultures, like the ancient and modern Greeks, eat most of the edible parts of the sacrifice in a feast, and burnt the rest as an offering.