Instinct and imprinting were the first scientific concepts in ethology. Spalding was able to prove that the behaviour of chicks after hatching from the egg happened even when they had no experience, practice or even information from the senses. Therefore the capacity was inherited. J.B.S. Haldane reprinted Spalding's essay "On Instinct" in 1954 to show how important it was for the history of ethology.