It was once a common custom in East Cornwall, when houses were built, to leave holes in the walls by which these little beings could enter; to stop them up would drive away good luck. In West Cornwall knobs of lead, known as pisky's paws or pisky feet, were placed at intervals on the roofs of farm houses to prevent the piskies from dancing on them and turning the milk sour.

An elf might be thought of as a big pixie, often depicted as a mischievous dwarf, such as the Irish leprechaun known for his pranks but also believed to know where treasure is hidden. Elves are sometimes depicted as helpers of magicians.

Pixies should not be confused with gnomes, which are also mythical diminutive humans but are deformed and live underground.

There are many theories as to the origin of pixies:

A.K. Hamilton Jenkin concluded after extensive research that they were an ancient race of small people who were conquered by the Celts but who lived a long time afterwards leading a furtive existence on moorland.

Robert Hunt was told by local people that they were small people in a state of decay from the earth who eventually turned into ants. It is therefore deemed unlucky to destroy ant's nests. However, a small piece of tin placed in an ant's nest at certain lucky phases of the moon, will be transmuted into silver by Pixie power.

Margaret Anne Courtney says that at the beginning of the nineteenth century in England, it was thought that unbaptised children would turn into piskys when they died, gradually going through many transformations, at each stage getting smaller.

When unmolested, Pixies bring good fortune to places they frequent; but they are spiteful if interfered with, and delight in vexing and thwarting people who meddle with them.

Vexatious pixies