Apple
The most famous legend involving the apple is perhaps the fruit from the Tree of Knowledge in the Bible, which made the first humans conscious. This was somewhat of a theft, and the golden apples of the Hesperides were also accessible only through theft. Heracles stole them through cunning, which according to von Franz suggests that "the apples have to do with consciousness and knowledge" (Animus and Anima in Fairy Tales, p. 48).
In Norse mythology, Idun had golden apples that granted the gods eternal life, and in the Arthurian legend, Avalon – the island Arthur travels to in order to die – is associated with apples. ("Avalon" roughly means "island of apples.") Thus, there is a general association between apples on the one hand and consciousness and death on the other. The fruit borne by the "tree of labor" was, for the alchemists, equivalent to the philosopher's stone.