That large portrait of your wealthy Aunt Jane, given by her and which you loathe but do not dare to take down from your wall; that large bookcase, too costly to discard, but which you hope will be more in keeping with your future home; these, and a thousand other like items are “white elephants”, costly, but useless
The allusion takes us to Siam. In that country it was the traditional custom for many centuries that a rare albino elephant was, upon capture, the property of the emperor, who even today bears the title, Lord of the White Elephant, and was thereafter sacred to him.
He alone might ride or use such an animal, and none might be destroyed without his consent. Because of that latter royal prerogative, it is said that whenever it pleased his gracious majesty to bring about the ruin of a courtier who had displeased him, he would present the poor fellow with an elephant from his stables.
The cost of feeding and caring for the huge animal that he might not use nor destroy, a veritable white elephant, gave the term its present meaning.
Incidentally, as a matter of English history, Charles I of England had the sad experience of receiving such a gift, a figurative, if not literal, white elephant.
In 1629, just at the time that the king, faced with a recalcitrant Parliament, was desperately trying to raise funds by any measures, even to the extent of bartering the crown jewels, the Emperor of Siam sent him an elephant and five camels.
Though the account does not say that the elephant was white, the cost of keeping the beast, estimated at £275 a year, was so great that the queen was obliged to put off her “visit to ‘the Bath’ to a more convenient season, for want of money to bear her charges,” for, as the record goes on to say, aside from that cost for feed and care, “his keepers afirme that from the month of September until April he must drink, not water, but wyne, and from April unto September he must have a gallon of vvyne the daye.”