Origing of "White Elephant"

This is the English expression for a gift that is more trouble that is worth, or an elaborate venture that proves fruitless.
In ancient Siam (modern Thailand), white elephants were sacred and could not be put to work. However, they had to be cared for by law because of their cultural significance. So it became the practice of Siamese kings to give white elephants to servants whom they were displeased whith it, because although was considered an honour on the surface to receive such a precious gift from the king, the servants were stuck with an elephant to feed that couldn't even be put to work.